9.3 identification help

[EricW]

Hey everyone. I’ve been trying to research what rear end is in my car and I think I have a 9.3 but is it Buick or olds/pon and what year. The car is a 1955 Buick Century but the previous owner, who has passed, swapped the torque tube for this rear end. There is a number cast on the center section in the 9 o’clock position (passenger side) 519281 with a larger 6 underneath. There is also another number cast on the 5 o’clock position (lower driver side) C309. Both of these are ok the outer flange of the center section next to the mounting bolts.

I cannot locate any numbers or letters on the axle tubes.

The research I’ve found shows the olds/pon number location and mine doesn’t seem to match up.

[EricW]

Here are the photos. Sorry one of the pictures comes out upside down. The ladder bars are not stock to my vehicle and have been added. It appears different brackets have been welded to the housing.

[monzaz]

it is likely a early 1952- 1956 era 9.3 rear. You have to pull an axle shaft.
if the axle shaft is 10 spline it is Pontiac 16 spline Oldsmobile
or vise versa...Have to check that out more. Hang on will try and get some research on it. Jim

[monzaz]

well that number that is C 30 9 is likley a date code C = month (MARCH) 30 = day 30th day of march and the 9 = the year 1949 in this case
It is NOT 1959 because i know what those castings look like and that is not one pictured.
So my best guess is a 1949 rear end Oldsmobile.
Jim

[EricW]

Thank you for this information. I bought a new pinion seal to replace the leaking one on the diff. I marked the pinion nut and counted the threads. I got everything installed and tightened it about 1/16” past where I marked it before taking it off. The bummer is it is still leaking and flinging oil all of the under side of the car where the driveshaft meets the pinion. Any suggestions to help fix this leak? Should I try to tighten the pinion nut more?

[monzaz]

you need to call us the number is on the home page of the web site. ends in 8155
JIm