Thought I would update this thread.... The 2.73 gears are a dog on takeoff with the M20 Muncie. We live in the mountains and pulling off on a hill was really hard on the clutch.
I tracked down a date correct ZM axle with the correct 3.36 posi earlier this year. It was really clean and looked like the axle bearings had been replaced but I media blasted, painted and changed the fluids. I was finally ready for a axle swap.
This past Sunday I swapped them and it went pretty easy. Since the new rear axle has the correct 3R pinion yoke, I had to change the universal joint back from the 1310 -3R combo joint. The swap was straight forward. I jacked it up on stands. Dropped the driveshaft. Disconnected emergency brake cables, disconnect brake line at piston and removed top holding bracket from top of cover, unbolted lower shock bolt, unbolted the u bolts and t bolts from lower shock mount to axle, unbolted front spring cup and lowered front of spring to ground and slid out axle.
After putting the new axle in in reverse order, I changed over the brake components to new axle.
I have not test drove it yet and I hope to finish up some small items like add friction modifier additive, torque some bolts and bleed the brakes. I then hope to test it out this weekend. I am hoping to see a big difference in take off as well as my speedometer calibrated correctly.
My plans now is to try out the 3.36 and see how I like it. Then have my original rear end completely rebuilt with a new posi carrier, bearings and either 3.55 or 3.36 depending how these go.
