Engine quits when tranny engaged?

A neighbor of mine has a 73 F250 with a 390 swap. It has been running fine lately and drove fine 2 weeks ago. But now he will start it and run it and as soon as he puts it into reverse or drive the engine dies. I thought it could have been the carb so i rebuilt it and it runs better (since it was horrible) but the problem persists. I checked the fluid it was a little low but not by much. Id really like to know what could be doing this. Any help would be greatly appreciated.

I had that problem with my truck a few years ago, although it was mainly when I put it in reverse. The dealership told me the filter in the transmission came loose and was sitting in the bottom of the pan creating the problem. Could be worth checking out.

[QUOTE=97F350]I had that problem with my truck a few years ago, although it was mainly when I put it in reverse. The dealership told me the filter in the transmission came loose and was sitting in the bottom of the pan creating the problem. Could be worth checking out.[/QUOTE

Ok i will check that out. Any other possibilities?

The converter is locked up.

The converter is locked up.

I figured that was the case at first. The only thing stopping me from making that decision is that it only sat for two weeks. Its possible i guess. Thanks!

Hey guys. I was browsing around and found this thread. My 1968 chevy k10 has similar problems. Would you let me know if you find out what it is?
Thanks.

Andy