I have an 88 Dodge Ram d100 with the 318 904 and I just recently put a body lift on it with 20x12 33x12.50 20s and every since then if I stomped the gas my truck jerks into neutral idk what that could be I did have to cut and extend my shift linkage bar as the instructions said to and provided me a piece to do so. I was think maybe when I cut it and welded it back up it wasn’t in the same position as it is supposed to be so It threw it off? I have also noticed that I can’t manually shift it into first gear and I think that has something to do with the incorrect angle of the shift linkage? I had to adjust it all for it to even shift in the first place, now every thing shifts fine except if I try to manually put it in first gear.

Are your engine and transmission mounts solid? It sounds like body torque is pulling o the shift linkage. If the body and engine mounts are solid, I'm thinking the angle on the linkage may be off.

I believe they are my truck was getting knocked out of gear once before like 6 months ago and I put new body mounts and it fixed it but now that I had to mess with the shift linkage rod it’s doing it again

Readjust the shift linkage. I had a blazer that would do that as well, but, my body mounts were shot.....