1993 Ford F-250 with a 94 12 valve Cummins
ZF5 speed. All destroked.com conversion parts.

I recently put a 12 valve Cummins in my 93 ford and used an adapter plate to continue using my zf5 transmission after replacing the 7.3 idi. All has went well for over two years until recently when I went on a two hour trip with no problems then the next morning I started it up and the truck squealed while turning left. I thought it might have just been my serpentine belt whining or power steering acting up yet everything felt completely normal. I then went up to third gear and was running probably 25-30 mph when I heard a rub or almost grinding noise. Yet no vibrations or anything crazy. Everything shifts completely normal and no synchros grind or anything. Moving the clutch in and out has no affect of noises. I have to be cruising in order for noise to come about. Im 99% sure the sound is coming from bellhousing area obviously. Drive shaft seems to be tight on my u-joints. Doesn’t even spit out any while in any gears. I haven’t got up to crazy speeds since this adventure and am gun shy now. Doesn’t seem like a throw out bearing nor my clutch. It’s a south bend single disk. Any suggestions to look for before I drop the Tranny would be greatly appreciated due to most likely having to pull the cab in order to do this project.

Hubs are unlocked but I did recently use the 4wd. The linkage is kind of weird due to the entire transmission sliding back 1 inch. I’ll put it back in 4wd tomorrow and then take it back out and see if it still makes noise. It doesn’t make noise when turning only the very first time the noise started it was while turning left. Hasn’t made noise while turning since.