Just got my 46r back in the van, trying to find source of shudder. Thought it was rear brakes, no, then posi clutches, so replaced limited slip oil. I can back up maybe 40 ft, then pulling forward it shudders-slips, not drastic but like something’s slipping and grabbing then it goes away. Could it be in the trans? I just got it back in AGAIN, I’m stumped, any ideas?