PLEASE HELP can any 1 identify this rear end

its in an old lancer , 61- 62 gasser The #s are 1634985 the car had a 413 engine in it .its written like a gear ratio 3.31 has a sideways 5 by where an X would be on an X head and it measures 52 inches roughly inside to inside backing plates .other #s kind of look like this
3 m o P. 114
c it is on the ground so we do not know if it is a sure grip
please write me if you know for sure or just add opinions to this thread , the big nut is held on by a cotter key and it has no pawl , but it has a keyway holding it in . THANKS FABO FOR HELPING