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Pilot Bushings
for
GM Gen III+ Engines
A precisely sized pilot bushing is essential to proper manual transmission installation. It supports and aligns the transmission input shaft on center during clutch release.
GM Gen III+ engine crank flanges were made shorter (closer to the block) than the Small Block Chevy specification by 4/10”. This means that most conversion applications use the rear bore of the crank — the one intended for the automatic transmission torque converter — for the pilot bushing. 
The following engines retained the classic SBC crank spacing:
- The 4.3L V6 LU3, all
- The 4.8L Vortec with manual transmission from 1999–2000, casting #312
- The 6.0L Vortec with manual or auto transmission from 1999–2000, casting #215
For a fuller discussion on LS / Vortec crank spacing, see this page.
Select your transmission
Our highest quality GM Gen III to GM Muncie / Saginaw transmissions pilot bushing.
Jeep T90 transmissions have a ~5/8” pilot tip diameter.
Two pilot sizes are used on the T14: early (1967–1971) at ~19/32” and late (1972–1975) at ~3/4”. All T15 transmissions used the ~3/4” pilot.
The Jeep T98 as found in the M715 and some FSJ trucks has a ~5/8” pilot tip. Verify your input shaft configuration before ordering, as numerous styles were used across different years.
1972–1975 Jeep T18s in some applications feature a ~3/4” pilot tip. 1976–1979 Jeep T18s as found in CJs feature a ~17mm pilot tip.
1976–1979 Jeep T150s as found in CJs feature a ~17mm pilot tip.
T176 transmissions make good conversion candidates for GM power. They feature a ~15mm pilot.
Two pilot tip sizes are used on the AX15: 1988–1991 at ~19/32” diameter, and 1992+ at ~3/4” diameter. Verify yours before ordering. NV3550s all feature a ~3/4” pilot tip.
NV3550 transmissions make excellent conversion candidates for GM power. They all feature a ~3/4” pilot.
All Jeep NSG370s feature a ~3/4” pilot tip.
Ford transmissions such as the NP435, T18 & T19 often make great combinations with GM engines. They all feature a ~17mm pilot.
Don’t see what you need? Contact us — we may be able to source or machine a bushing for your application.
Installation Requirements
Removal of the old bushing and cleaning the crank bore is required prior to installation. There are a number of official and unofficial methods to remove the old bushing or bearing. Hydraulic removal using inserted grease behind the bushing (or a wet paper towel) and a precisely sized rod is a classic approach. Our preferred method is a slide puller available from your local parts store as a rental tool.
A proper drift tool or driver is recommended for installation. Do not coat oiled bronze in grease, as this plugs its pores and prevents proper lubrication afterward. Soaking the bushing for a day or longer in clean engine oil prior to installation is preferred. Freezing the bushing and lightly warming the crank can ease installation. Pilot bushing and transmission input shaft damage are inevitable if the bellhousing and transmission are not centered concentric and parallel to the engine face. We recommend using a dial indicator to verify centering on the bellhousing bore.