I did a 4.0 swap with clutch, flywheel and all that a while ago and ran it like that for a good year. Then one day at a mudding spot I got stuck a a good mud hole, and bent my cross member for trans (I think that when it got bent) and lost the ability to use any gear but 5th after I was pulled out and got onto the road I regained all my gears. The next day I was driving top my buddies to replace parts and while at a red light lots all gears. I could start the truck in gear and accelerate but not shift into any other gears. Then I replaced Master cylinder, slave cylinder, TOB, Transmission (M5OD) and flywheel, clutch pressure plate and clutch disc. I Put the side of clutch disc that says to flywheel surface against the flywheel. I though maybe the slave wasn't bled right and pushing out as far as it should so i put washer behind the slave cylinder to shim it forward changed nothing, still could not put it in gear. With all drive shafts out I can shift into gear fine while at idle or with RPM's rising. Once I put the drive shafts in I can no longer shift into gear from idle and when I leave it in gear during cranking to takes off. If i lift the rear wheels off the ground I can shift into all gear as if I am accelerating on road. I am puzzled. I thought the cross member was the cause so I took it off and put a jack under the trans to hold it and still was unable to shift into gear.