Hot Rods 10 bolt ID

I have a GM 10 bolt rear end under my 37 Buick and need to change out the ring gear and pinion but nothing I can google up shows what it came from. The code with the spacing used is: 6AX C053 2
I was told it was from a 70 El Camino but it was just laying out on the ground at the yard I bought it from. Everything I can find shows a three letter prefix but this one is definitely the letter "6" followed by AX. There seems to be a change between 70 and older and 71 and newer in the 8.5 inch 10 bolt so one really needs to know what he has. Thanks for any help;

Evan

 

Found it. 1984 El Camino.

 

this help?

http://www.348-409.com/differential.html