1963 Diff

[Frank Murch]

About 2 years ago, I found (through Jason - thank you jason) a limited slip differential. I have the original non - limited slip.  It is a good diff, it needs nothing.  

Does anybody ever buy these, and does anybody need it?  I can see this sitting in my garage for the next 20 years.  Any ideas??

[Jason Edge]

There has been a constant demand for the optional controlled (limited slip) rear end over the last 25 years, but there didn't seem to be much demand for the regular rear ends up until about 5 to 10 years ago, but I have seen the demand continually increase for regular rear ends as no one is reproducing these, or the axles, or the differential, and as these cars age out the rear ends are starting to go ... and instead of it being a nice upgrade as in the case with the limited-slip, it becomes a matter of just keeping the car on the road when the rear end goes. In the past 5 years I have had a pretty steady demand for complete rear ends, just the differential, and axles.   I'm guessing I have been moving 1 to 3 rear ends a year, which about equals the # of parts cars I have brought in recently. 

The main thing to consider is the rear gear ratio. There is a bigger demand for the 3.21 gear vs the 2.94 gear since about 2/3's of the cars came with AC and that 3.21 gear. I have had maybe on one or two occasions where someone specifically asked for the 2.94 gear for better highway mileage and speeds. So if you sell be sure to list gear ratio.
 

[Jason Edge]

Tony that is incorrect. A rear end differential gear ratio represents the number of times the driveshaft will turn for each turn of the wheel. For example with a 3.21 gear, the driveshaft will turn 3.21 times for each complete rotation of the wheel.  More technically, it is the number of teeth on the ring gear divided by the number of teeth on the pinion axle gear. 

This is why a car with a lower number has higher top end speed and potentially highway speed mpg performance since the driveshaft is rotating less times per rotation of the wheel rotation.  Likewise a car with a higher number means more rotation of the driveshaft per wheel spin and allows more use of the engines hp and torque through the lower speed range which makes them more ideal for city driving ... or drag racing.

[Frank Murch]

UPDATE It is a 3.21 from an AC car