[kaui56]

Simple man!

Jack the back end of the truck up so that both rear wheels aren't touching the ground. Grap one of the wheels and spin it. If the wheels go in a opposite direction it's not a posi. If the wheels spin in the same direction it's a posi.

Have your truck in gear, as in park if it's an automatic, or in gear if it's a standard.

Oh yeah.... Don't have the emergency brake on either or else nothing will spin. LOL

you dont want it in gear...you want it in nuetral...if its in gear they wont spin.