Convert 9" open to Posi

[69 Mach 393]

I have a 9" open rear end with 300 gears and 28 splines. How is the best way to convert to posi with 350 gears.

 

[69 Mach 393]

I have found a disk brake set up out of a 76 Lincoln .Will it bolt up to my 9" in a 69 Mach 1.What else would be involved.

 

[Edbert]

You must buy the LSD unit (Tru-Trac is the Ford version of "posi"), then a 3.50 ring and pinion set and have them installed. The tolerances are very tight and should not be done on a workbench by a novice.

Ford basically sold two different 9-inch housings from the mid '60s onward. The small bearing and the large. Mainly F-series vehicles and Broncos got the large and passenger cars got the small. Measure the outer flanges of the two axle tubes, if they are the same you're all set.