AUTOMATIC TRANSMISSION INSTALLATIONS (TH350, 700R-4, 4L60E & TH400):
There are (4) types of automatic transmissions that can be used for both 2WD & 4WD models: the TH350, 700R-4 (4L60), 4L60E, and TH400; the TH350 being the most popular choice transmission with the 700R-4 and 4L60 being close behind. We have added the TH400 for high performance applications.
If the engine and transmission are moved back at any great length, you will find it nearly impossible to install the original transmission dipstick assembly. We offer special flexible dipstick assemblies from a company called Lokar Performance Products.
PN23-0001 - GM TH350 & TH400 flexible dipstick assembly
PN23-0002 - GM 700R flexible dipstick assembly
PN23-0004 - GM 4L60E flexible dipstick assembly
If your vehicle is equipped with the column shift automatic transmission controls, a slight modification may be required to the control arm that is located on the inside of the firewall. This arm will need to be bent back closer to the firewall for the necessary clearance around the exhaust system. Make sure that the lever is parallel to the firewall after the modifications have been performed.
The best selection for a 2WD V8 installation is the TH350. This transmission case length is approximately 2-3/4" shorter than the TH400 and, when purchased with the 9" tailhousing, can be installed without driveshaft modifications. The TH350 will have minor modifications, whereas the TH400 will require major modifications to the firewall and tunnel areas. Modifications may vary depending on the engine selected.
TH350 PREPARATION: TH350 Preparation for 2WD Conversions
When installing the TH350 into a 2WD vehicle, we recommend using a transmission which has a 9" tailhousing. This will enable you to eliminate driveshaft modifications. If you are replacing an automatic transmission, you can retain your stock shift linkage with minor modifications. If you are replacing a manual transmission, you will be required to purchase a new automatic floor shifter. This conversion will also require the elimination of the two ears of the transmission as illustrated in the GM Automatic Transmission section of this manual. We offer a B & M Sport Shifter, AA Part No. 715680, for vehicles without a console. TH350 2WD dwg
700R-4 & 4L60E PREPARATION: TH350 Preparation for 2WD Conversions
Most 2WD S10/S15 vehicles were equipped with the TH200C transmission (which is very light-duty), or 700R (60 degree bolt pattern) transmission. If you want to retain an automatic overdrive transmission, you have two suitable choices: the 700R (90 degree bolt pattern) transmission from a full-size GM vehicle or the 4L60E computer controlled transmission. There will be no modifications necessary to the transmission case in order for it to fit into your vehicle. The overall length of these transmissions will be exactly the same as the original transmission. The 4L60E transmission will require a reluctor ring and sensor which is normally located on the tailhousing.
The TH400 into the 2WD S10/S15 will require the use of the original TH400 rubber crossmember support. Slight modifications to your existing crossmember may be required. If you are replacing the 700R automatic transmission, you will need to change the shift indicator and rework your existing shift linkage. If you are replacing a TH200C transmission, no modifications to the shift indicator will be required. If you are replacing a manual transmission, then you will need to install a cable-type floor shifter. Most TH400 conversions will require extensive floor pan modifications on 2WD installations. The TH400 output shaft has 32 splines and will NOT be compatible with your existing driveline. Approximately 2” of driveshaft modifications will be required. TH400 2WD dwg
2WD CONVERSION PARTS
FOR S10/S15 V8 & 4.3 V6 CONVERSIONS
The parts listed on this section are compatible with all 2WD S10/S15 V8 & 4.3 V6 conversions. Refer to the General Conversion Information Section of this manual for additional conversion considerations.
We manufacture bolt-in motor mounts for the early S10/S15 2WDs. They work in conjunction with the stock 2.8L frame mounts. If your vehicle was equipped with a 4 cylinder, it is necessary that you purchase and install a set of stock 2.8L V6 frame mounts, GM Part No. 22188284. On 1990 & newer 4 cylinder applications, you will need to purchase a set of 4.3L mounts (both frame & rubber mounts): GM# 22188970 (rubber), GM# 15602789 (left steel mount), GM# 156674856 (right steel mount), and used in conjunction with our mounts P/N 713123.
On 2WD S10/S15 blazers replacing the 2.8L, the stock motor mount perches were 1” higher than most S10/S15 pickups. To compensate for this higher stock engine location, use the drilled hole in the mounts rather than the slot. If you select a lower position on a vehicle that was not equipped with this 1” higher perch, you will have starter motor clearance problems. Modifications to the crossmember may be required; or simply using the small diameter hi-torque starter will offer the necessary clearance. If your vehicle is a later model S10/S15 that came equipped with a 4.3 V6 and you are planning to upgrade to a V8, we manufacture a bolt-on mount for this installation.
PN713123 - Chevy V8 to stock 4.3 V6 motor mounts (used also on Astro Vans)
These motor mounts listed above are slotted for fine-tune adjustments. On vehicles retaining the air conditioning, the engine must be set to the furthest rear position available on the motor mount. When this is done, clearance on the A.C. evaporator housing becomes crucial on the passenger side exhaust manifold. We manufacture a sheet metal cover that will allow ample clearance between the manifold and housing. (P/N 716421)
These conversions are compatible with most stock GM oil pans and will not require our special rear sump oil pan.
For 2WD conversions, you will be able to use either the "SlickFit" headers or stock GM manifolds. We manufacture two types of 2WD exhaust headers. The 2WD “SlickFit” headers are furnished with both sides dropping downward and will permit clearance of the A/C evaporator housing on the passenger side. The exhaust will run directly above the A-arm assembly so that modifications will not be required. The 717052 driver’s side header also drops down and allows clearance for the steering driveshaft. The 717057 driver’s side header has two primary tubes that go over the steering shaft and two that go under. Our SlickFit headers will not work with Trans-Dapt or Hooker Header motor mounts. Headers are not compatible with lowered engine positions. NOTE: Our headers are not designed to fit Chevy small blocks with angle port heads.
DO NOT USE any type of header wrapping material on the SlickFit header or you will void the warranty.
Our headers are manufactured with a 5/16” header flange and 16 gauge tubing. Both types of headers use a slip-type exhaust connection which aids in additional clearance when exiting from the engine compartment. These headers are available in Chrome or Non-plated (NP). (We do not offer headers for the 4.3 V6 applications.)
PN717052 - SlickFit headers, Chevy V8 2WD (manifold style)
*PN717057 - SlickFit headers, Chevy V8 2WD (tubular style 1-1/2” TUBING)
*(Should not be used on 1982 & 1983 vehicles)
The GM manifolds that we recommend are designed for engines with the dipstick on the passenger side of the vehicle. The manifolds should be limited to engines 1978 & newer that have the special bolt pattern on the back exhaust port. The manifold numbers are GM Part No. 14007400 & 14014500. Also, 1982 & newer Camaros use exhaust manifolds #10108437 (right) & #10106123 (left).
Tranny ear-exhaust Transmission ear should be removed to aid in exhaust clearance. this transmission was not modified yet.
2WD ENGINE CROSSMEMBER MODIFICATIONS:
On 2WD conversions that are using the stock exhaust manifolds, it may be necessary to modify the back side of the engine crossmember mount in order to allow access for the vertical exhaust dump from the stock manifold. This modification is only required on the driver's side of the vehicle. The engine mounts are adjustable so that the engine can be slid back for maximum clearance. These modifications could be made by the muffler shop if necessary.
We offer an aluminum single core radiator and a 2-core Aluminum radiator. Both these options work well with a larger engine into these vehicles. These radiators are equipped with the proper hose connections and built-in transmission coolers.
PN716694-AA - Rad-A-Kool Aluminum 2 core tig welded radiator (1982-93 w/ automatic transmission)
FLYWHEEL & FLEXPLATE:
When using an automatic transmission, we recommend that you use a 168 tooth flexplate. In both applications, make sure that you do not obtain these parts from a Chevy small block 400 that was externally balanced. Obtaining the wrong parts will cause severe vibration in the drivetrain. Make sure that your flywheel is compatible with your engine selection.
In manual transmission conversions, you can use either the 153T or 168T flywheel. For more information, refer to the Transmission subheading in the General Information section of this manual.
MANUAL TRANSMISSION BELLHOUSING REQUIREMENTS:
If you are using a manual transmission, you will need to use our bellhousing kit. This bellhousing is the only proven method of adapting your manual transmission to the new V6 or V8 engine. Our kit comes complete with a internal release bearing, pilot bushing, and hardware. The manual transmission conversions are NOT compatible with vehicles 1982-83 that are equipped with cable clutch controls. We highly recommend our 11” pressure plate with this bellhousing; and the 11”, 1”-14 spline clutch disc is required.
PN712547 - GM bellhousing kit
PN716102-P - 11” Pressure plate
PN716102 - 11” Clutch Disc
TORQUE CONVERTER INFORMATION:
If you are converting to an automatic transmission, any GM stock torque converter will work with your TH350. If you are using a 700R-4, you will be required to purchase an aftermarket lockup converter kit. We offer a lockup bypass for the 700R transmission.
PN24-700R - 700R Lockup Bypass Kit
Your transmission crossmember will remain in the stock location. However, you will need to elongate the holes in the transmission mount in order for them to reach the new TH350 motor mount location. On some crossmembers, the location can be adjusted along the frame rails for final positioning.
If you are using a TH350 transmission with a 9" tailhousing, you can usually eliminate any driveshaft modifications when doing this conversion. If you are using a standard 4 or 5 speed or 700R-4 automatic, no driveshaft modifications should be required. However, if you locate the engine further back towards the firewall you may need to shorten your driveline approximately 1". Driveline requirements may vary depending on various TH350 tailhousings and transmissions being replaced.