Converts the 3-bolt output flange on GM 6L80, 6L90, 8L90 and 10L80 transmissions to a U-joint slip yoke so you can run a one-piece driveshaft.
Pulled a 6L80 out of a Camaro or CTS-V for your LS swap and found a three-bolt flange on the tailshaft where you expected a slip yoke? Or tired of replacing the rubber flex disc on a modern GM automatic? This adapter bolts to that 3-bolt output and gives you a 1350-series U-joint yoke, so a driveshaft shop can build a plain one-piece shaft. It is listed for the 6L80, 6L90, 8L90 and 10L80 automatics and the TR6060 and TR3160 manuals, with a depth spacer in the box for the 8L90 and 10L80.
Many late GM drivelines do not use a sliding yoke at the transmission. The output shaft carries a companion flange, and the driveshaft bolts to it through a rubber flex disc or a CV joint. That works in the donor car with its two-piece shaft and carrier bearing, but in a street rod, muscle car or truck swap you usually want one tube, two U-joints and nothing rubber. This flange yoke turns the three-bolt pattern into a standard U-joint ear, which is what a conventional one-piece shaft needs. The reference design for this kit, T35-GMFD-01K, is machined from 6061-T6 aluminum, uses a dual 96 mm and 110 mm bolt pattern, and puts 3.000 inches from flange face to U-joint centerline.
Look at the tailshaft. If you see a three-bolt companion flange rather than a smooth seal bore with a slip yoke inside it, this adapter applies. Measure the flange bolt circle so you know whether you are on the 96 mm or 110 mm pattern. A vibration is not always the driveline, though: a 6L80 with converter shudder can feel similar at light throttle, so read our 6L80 TCC shudder diagnosis guide before blaming the shaft. If you are still choosing which GM automatic to swap in, 6L80 vs 8L90 differences covers what changes between them.
Listed for GM 6L80, 6L90, 8L90, 10L80 and 10L90 automatics plus the TR6060 and TR3160 manual transmissions. On the differential end it is also listed for the 2005-2006 Pontiac GTO. The included spacer is required only on the 8L90 and 10L80 to set the yoke at the correct depth; leave it out on a 6L80 or 6L90. Output flanges are not identical across every application, so measure your bolt circle and pilot before ordering, or send us the transmission and the vehicle it came out of. More swap and rebuild parts are on our 6L80 parts page.
Support the transmission and remove the factory driveshaft, marking any parts you plan to reuse. Clean the flange face so the yoke seats flat, fit the spacer into the yoke pilot bore if you are on an 8L90 or 10L80, then torque the three bolts in a cross pattern. Run new 1350-series U-joints and straps, then have your driveshaft measured with the yoke installed and the vehicle at ride height so the shop can set length and phasing and you can check pinion and transmission angles. If the transmission is coming apart for the swap anyway, the 6L80 bell housing and a 6L80 friction plate kit are worth having on the bench. Fill with Dexron VI once it is back in.
| Fits transmissions | GM 6L80, 6L90, 8L90, 10L80, 10L90, TR6060, TR3160 |
| Also fits (diff side) | 2005-2006 Pontiac GTO |
| Function | 3-bolt flange to U-joint slip yoke conversion |
| Driveline | Converts factory two-piece to one-piece |
| Material | Precision-machined aluminum |
| Included | Flange, mounting hardware, 8L90/10L80 depth spacer |
| Weight | 2 lb |
| Reference part | T35-GMFD-01K |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
Only if the output has a three-bolt companion flange. Transmissions with a conventional slip-yoke tailshaft already accept a standard driveshaft and do not need it.
The kit is built to the T35-GMFD-01K pattern, which uses a 1350-series U-joint. Tell your driveshaft shop so the tube, weld yoke and joints match.
The spacer is for the 8L90 and 10L80 only. It goes in the yoke pilot bore to set the correct depth. Do not install it on a 6L80 or 6L90.
No. The adapter is meant to replace the flex disc or CV coupling with a U-joint, so you will need a one-piece shaft built to length after the yoke is installed.
The reference design is a dual pattern for 96 mm and 110 mm bolt circles. Measure your flange before ordering to be sure.
