My First Mopar- 1966 Barracuda project

with the longer slip yoke you used, do the internal splines go right to the end? many of the longer ones don't, just giving a better support in the tail housing bush. this can mean only a short spline engagement though, in your pics the yoke looks quite a way out of the trans'. a simple spacer at the axle pinion will give more engagement and i'm pretty sure they're available through 4x4 suppliers for (modified for offroad) explorers.
neil.