I bought a 31-spline, positraction Ford 3rd member with 3.50 gears from a swap meet. The guy said that it was from a truck and that it was 9 and 3/8" across so I'd have to grind a 1/16" off each side of the housing to get it to fit in my Ford 9" housing. He said this was quite commonly done and that there are a bunch of videos on youtube showing you how to do this, but I can't find any. Has anyone ever done this? Did you have any issues with it? My axle is from a 1957 Ranchero and is currently non-posi with highway gears roughly 2.97's (they came with the car so I don't know exactly what they are).
I remember something like you described, grinding the case to open it up where the ring gear slips through, but I don't remember the details. If you don't get an answer here call Currie Enterprises. I just bought some parts from them for the rear end in my rpu project and they were extremely helpful. Here, I found this on the net. Scroll down to where they discuss the 9 3/8 in a 9 inch housing . It has the heading 9 1/2 there: http://kevinstang.com/Ninecase.htm Don
You gotta read this. http://www.jalopyjournal.com/forum/threads/ford-9-3-8-axle-questions-splines-ratios-etc.292675/
I've seen many guys go the other way and put a 9" differential in a 9 3/8" housing. Haven't heard anyone going the other route as you're looking to do.
Same here, 9 inch into 9 1/2 housing. Infact getting ready to narrow the housing 5 inches. My only real concern would be grinding the housing right at the gasket sealing area. Have to be careful or i would think it could be a problem spot for leaks.
My friend Jimmy did it. I don't remember how much grinding was required, but it didn't leak when he was done. He took out a 4.56 spool and put in a 2.80 posi for power tour. Posted using the Full Custom H.A.M.B. App!
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