Slip in reverse
 

Hello everyone, first time posting. My name is Kason and I have a 1999 Chevy Silverado Z71. 267k miles on original engine, tranny was replaced at around 200k by previous owners (ex-in-laws) they kept it meticulously maintained and it had 253k when I got it. Admittedly, I really have not driven it that much Rear diff had gone out with the OEM GOV-Lock, I ended up doing a rear end swap to an open differential. Shortly after, my tranny started to slip in reverse. In all forward gears, it’s as strong as ever. Doesn’t slip, revs don’t hang or take off. Only problems I have when it’s in reverse. Sometimes it will “catch” and it will work fine for a few feet then start slipping again. What could I be looking at here, what should I look for? I’ve been told it could be a matter of replacing TF, and cleaning/replacing a screen. But I’ve also been told that the entire tranny would need to be rebuilt. Thank y’all for having me! I’m not sure if I posted this in the right area! My apologies if I didn’t!