Most older 1/2 ton and smaller trucks/jeeps/etc use 1310 sized driveline parts. 3/4 ton stuff uses any thing from 1310, 1330 (Ford) or 1350 -- so be very careful if you are pulling from 3/4 ton stuff - they look real close but are not...
But it isn't as easy as mixing and matching used stuff unless you swap the entire driveshaft for another driveshaft.
If my driveline splined section was worn/bad/etc, I'd just replace the whole thing with new or have the exisiting one rebuilt by a professional.
Now if we are talking offroad wheeler only - I'd build my own with square tube!