I actually had to put the 4 speed back in, but to answer your other questions, yes, the xmember bolted in perfect, the speedo cable is the same, i would swap drivelines anyway to be safe(especially if you already have it), and as far as the 5th gear thing goes i have no clue, i never drove with the 5 speed, i am keeping the xmember and five speed till i have the means to modify it to fit, maybe you could cut the xmember mounts off and move them back, i noticed there were ridges in different spots on the frame where the mounts would be welded to accommodate either a 4 or 5 speed, even the bolt holes were there, about 2" back.
hope this helps, Jason
be sure to let me know how it goes.