90 rear measures about 44 inches collapsed and around 47.5 inches extended to right before the splines are showing. Simple math shows about 3.5 inches of slip. Flange to flange on my mildly lifted 85 is about 46 inches. So it should work besides the flanges being a little off. If I ever need it I guess I have it. The only reason why I am looking at keeping the 90 rear driveshaft is because the u-joints on it have only about 6000 miles on them. The ones on the 85 I assume are stock with around 160,000 or something like that on them. If they ever go bad I can just swap driveshafts.
Having extra drive shafts is never a bad thing
