Ok so here is one for you Jeep techs. i have an 88 comanche 4.0 with a ax15. and 231 transfer.
when I start to drive its fine. shifts into 1st, 2nd,3rd and so on.. after I run it for a while it starts to get harder and harder to shift back into 1st or 2nd gear. If I'm coming to a stop and slowly try to put it into 1st gear ( as long as I'm not at a complete stop it will go into gear) its when I come to a complete stop and go from N and then try to go into 1st or 2nd it won't go in. i have to force it.I tried changing the fluid 10w30. It only does it after its warmed up. I'm thinking its in the transmission. but not 100% sure. let me know what you guys think.