79 transmission reverse gear

[Kyle20r4spd]

Hey guys, just started my new account and already have questions. My truck has the l43 4speed and it pops out of reverse quite often. Its really annoying to have it pop out all the time. I'm not sure what the problem is so any help would be appreciated. It's a 1979 4x4 with a 4inch lift, original 20r and 4spd rolling on 33's. I would post pics but I'm a newbie still so not sure how yet.

[Nimyad]

It's a weak transmission, mine did the same thing so I promptly replaced it with a later model transmission.

[Kyle20r4spd]

Would it be better to replace it with a 5spd or a rebuilt 4spd?

[Rocksurfer]

5 speed would be best and get one 85 and up, early 5 speeds will not last. FYI if you go this route you will need to relocate the trans/tcase crossmember further back, and you will have to mod the driveshafts.