[Rev]

What you might have is a CURRIE TSD (torque sensing differential). They work by using the "side loading" that occurs in the spyder gears ,when you mash the gas , to put pressure on the clutches that equalize torque to both wheels. Without heavy torque to the differential, that just doesn't happen. This is supposed to deliver somewhat equal torque to both wheels when you nail the throttle.

Now, having said all that, I changed mine to a spring loaded Ford Traction-Lock because I found that the Currie TSD was not reliable all of the time. Sometimes the TSD seemed to not deliver enough traction to the low traction side.

I spent another $150 or so to correct that short coming at a local shop.

BTW, it sounds like you might have a 3.00/1 which is a very common ratio and very useful with an auto tranny.

Rev