Originally Posted by JeffE
I have a 48 Pontiac that I plan on street rodding by putting in a sbc 350 and 700r4, making it more of a highway cruiser. My question is has anybody done this and used the stock rear end ? How strong are these rear ends ?
What size ring gear are these ? Any info ?
Look at it this way....the most powerful motor that was used by Pontiac in 1948 was rated at 220 lbs/ft of torque. If your motor will make that torque or less, then use the original diff. If you plan more power than that, then replace the diff with a later, stronger unit. I believe the original Pontiac diff was hung on leaf springs and had an open driveline. The rear track (centerline of the passenger side tire to the centerline of the driver's side tire) was 61.5", so take a tape measure and find a boneyard donor that has measurements close to that with leaf spring pads on the tubes. Brakes were internal-expanding shoe, hydraulic type, so any later model diff that has the spring pads and ~61.5" track should work. I might start off looking at Gen I Camaros.