What options are there for the d70 in the rear of
the M-715

It is not a standard d70 the shafts are something like 23 coarse spline

Check out www.m715zone.com they have tons of info about that axle. I seem to remember you can get a Detroit pretty cheap.

A co-worker of mine put a Detroit Locker in the stock rear axle of his M-715 several years ago. Pretty easy install as the D70 they used has the two piece carrier so the Detroit swapped in just like a 14-bolt version would.

What options are there for the d70 in the rear of
the M-715

It is not a standard d70 the shafts are something like 23 coarse spline

The 23 spline was the standard spline count in a Dana 70 before they started using 35 spline. This is also a .500 offset pinion 70 which doesn't affect the locker choice but does affect r&p choices.

Gus

Detroit Locker manufactured by Tractech. Part# 225-s-14

This is the one I have in my M715. Took longer to pull out the axle shafts than it did to put the locker in. Slide under with an Impact, a couple sockets, and a prybar and 10 minutes later your done.

Randy's R&P and Reider should both have them on the shelf. I run a lockrite in the front, but there are many choices up there, it is a normal 30 spline 60.