It sounded like I ran over a huge pothole but then the Bronco stopped moving and stalled. I turned the key off and opened the hood thinking maybe I blew something, but it all looked normal. I turned the key back on and it started right away. Moving the truck to drive however didn't cause the truck to move. Reverse also didn't work. I locked the wheels and put the 4x4 on and heard some grinding, but it did move. I put the truck back in park and checked to see if anything was hanging on the underside. All looked normal. I drove home with it in 4x4. What do you think is wrong? I expected the transmission, but that would effect the 4x4 as well from my limited knowledge. Next thought is maybe linkage or loose gear in tranny that just slipped loudly. I'll check out some more tomorrow, but has anyone heard of anything like this? It's a 90 ford bronco so she's getting up there in age. This may be the one that causes me to throw in the towel. Thanks folks. -Dave

I have absolutely no knowledge about cars other than Hondas, but here is what sounds logical to me.

If your Bronco usually uses only rear wheels to move, and it won't move by using rear wheels only, but wants to move using 4x4 (means all wheel drive) then perhaps something that brings the power to the rear wheels is broken. Try jacking the car up on jacks, and turn on 4x4 and put it in drive and see if all wheels turn.

If all this makes no sense - ignore me :)

Well, lets think of the parts that would stop the car in 2wd but not four. Power is distributed after the transmission through the transfer case and then to the differential in the back. I'd check those first, but I'm sorry I don't know much about your truck.