Axle ?'s

[truckinbean]

Is there any way to find out what axle length and spline count I need without pulling an axle in my 2wd 77 Blazer. The axle housing is out of a newer chevy pickup (81-up) so I've been told by a few different shops, but I don't really know since it was in there when I bought it.

Here's what I do know, if it helps:

10-bolt housing
5x5 lug pattern
Had 2.73's with an open diff before I had 3.73's put in
~64" between flanges
~43" between center of spring perches

Any info or links would be great

Thanks in advance, Ben