Help identifying GM differential

[radio747]

I picked up a differential at DVAP which said it was from a 70 Chevelle. It has the casting number 1385724, which sounds like a Buick or Oldsmobile. The pinion # is 1231463, and the gear ratio is 2.73(we think). I need to change the gear ratio to high 3's to 4.1. Can I get there from here? What gears are available?

Thanks,

Steve

[monzaz]

Hello glad to see you using the site...
Off we go-
This is a 1968-1970 BUICK SKylark rear differential
10 bolt 8.2 Ring gear
Pinion shaft is 1.875
Pinion spline is 27
Gear ratios available are 3.42 and 3.64 AFTERMARKET Fab Craft / and J d Race sell them (459.00 a set They are machined by Richmond gear engineered By Fabcraft Metal works)
Posi units are custom modified By J D Race 439.00 Auburn units
Rebuild kits are 95.00 (included everything to install the posi and gears / Bolts bearings races shims marking compound inspection cover gasket, pinion seal Pinion crush sleeve, Pinion nut etc. EVERYTHING...)

Steeper gears are only available if you FIND THEM in a rear like 3.91.

If you need a steeper ratio it might be a better plan to find a Chevy 10 bolt or Pontiac or 8.5 10 bolt - Obviously 12 bolt chevy will have steep gears and most selection.

Jim
J D

[radio747]

Thanks for the quick reply. This rear end has 2.73 gears. I spoke with Brad with fabcraft. He said I might need a new carrier for the 3.64 gears. Is that true? How much more is that.

Thanks,

Steve

[monzaz]

All the prices are posted for you Posi gears and rebuild kit in the previous post . Jim