Rear end help

I am trying to figure out what this Rear End is.
It is the 1940 Willys coupe that I am working on. My dad built that car in te 60's but doesnt remeber what exactly the rear end is out of. He said the best he Remembers it is from a Mercury. It has 10 Bolts holding the Rear Cover, And uses a 5x5 1/2 Wheel bolt pattern. Any Help would be Greatly Aprecctaited.
Will take some Pictures next time I am there.
Most likely built in the early to mid 50's.

Thank You in Advance.

 

Possibly Dana 44? Ford truck or pre '52 Mercury had that pattern.