I have a weird problem with the T-18 in my 79 F250 4x4. I have no drive from clutch to back of transfer case. I pulled the cover off the top of the trans and everything looks ok to me. When spinning a rear tire the driveshaft-transfer case-and main shaft all spin with no noise or drag. When looking through the clutch fork window in the bell housing I can see the pressure plate isn't moving but I can't see the input shaft. Could the input shaft be broke? I unhooked the clutch linkage thinking it might have been engaging the clutch but no change. Hate to pull the trans if I don't have to. any ideas? (in the picture the whole shaft spins with the driveshaft but not connected to flywheel)

 

So the engine will run, but when you put it in gear and let out the clutch, the vehicle does not move, right? Any noise associated with doing that?

And with the engine off, with the wheels up, you can turn the rear wheel and the shaft and transmission guts all turn, right? Any noise or resistance?

Have you tried turning it that way with the engine off and trans in gear?

With the top off the trans you should be in neutral to start with.

If it turns freely from both sides with the trans in gear, I don't see any choice but to pull the trans and take a look at the input and clutch disc.

 

The strange thing is there is no rubbing or grinding sound when the driveline is spinning. I need to take it apart this weekend and see what happened.The input shaft is spinning from the transmission side.

 

Well that answers that.

 

Side step the clutch at 7000 rpms or something?

I'm sure this happens from time to time, but you may have posted the first picture of it here!