On the rear axel, stamped into the housing of the drivers rear siade is the number
WA 415 and it has the 12 bolts holding the cover in place.

The guy I got the truck from said it had 3 73 posi trac gears.

How can I verify he is correct?

Thanks in advance

oh ans IF we decide to swap the engine and trans to a 350 small block with a 700R4 trans, do I need to change out the rear end?