[cmefly]

You can also just buy a used third member. I picked up a 3.50 detroit locker 31 spline for my 65 Falcon last week for $300.

 

[cmefly]

That's a good idea. I may just wait for a used one to pop up. Any suggestions of where to look?

Used third members can be found on Craigslist and Ebay. They sell in the $300-500 range for used and $500-900 rebuilt. take a look at your current rearend and determine if you have the short yoke or the long yoke. you will want to keep the same length so your driveline will have the correct length. the width is not as important as you can get a conversion ujoint to fit. most yokes are in the 3 5/8" width on the 9" some are 3 1/4" like the early mustangs/Falcons use. Most will use the 1 1/8" cap. I would stay with a TRAC-LOC style posi, Detroit lockers are not the most friendly on the street for some.3.25, 3.50 and 3.70 are the most used gears for street use.