Here's what I have. A V6 LWB front diff housing, LSD from a Starion going into an 88 SWB. Everything lines up great except for the drive side (left)axle shaft. This is not a spline issue it's a diameter issue. The 4cyl axle is smaller so this needs to be upgraded. When I assembed this the first time I thought the axle was engaged but a quick shift in to 4w and I realized something was wrong. I put the question up a few months ago regarding the axle and there wasn't a positive consensus to which axle I needed.
So keep this in mind, and of course be prepared to pop some ball joints to get the axle shaft out.