T-18/D20 Linkage Slip

Has anyone with a T-18 married to a D20 w/ a 304 had a problem with the D20 slipping out of 2H on a high speed (55-65mph) highway downhill? It seems I have tried to adjust the linkage several times but can't get it right. Any suggestions? Thanks!!

 

Does it feel like the transfer case is shifting positively into each position or does it just kinda go in? If not positive then I'd suspect the linkage adjustment or possibly the detent springs/balls being worn. If it does feel positive but still does it I'd check the transfer case input gear (bull gear) and see if the nut has backed off. If that's ok, then check the slider gear where it engages the input gear and see if the spline area is worn. Very common on a high mileage 20 for the gears to wear where they spline together and cause this problem.

 

Forgot to mention, check the simple stuff first. Linkage not hitting body, motor and transmission mounts in good shape, body mounts in good shape not allowing shifting of the drivetrain to body clearances.

 

Thanks, Nick. The D20 was rebuilt when I blew out my T150 and replaced it with a rebuilt T18. As far as feeling positive, it sort of slips and pops, if that is any way to describe it. 4H is a positive, as well as 4L, but 2H seems to have a longer swing to it...again, if that makes sense. The transmission and motor mounts are only 2 years old, and the body mounts are 4 years old. I'll check the input gear and spline to see if I have any premature wearing due to not being mounted properly. I did not have to cut the tub at all with the marriage and used only the 1" adapter for the bellhousing.