I have looked at a number of A/T cars recently. They "claim" to have 1800, 2600, 3000, etc. stall convertors. How can one tell, or estimate the stall of the convertors. Is there some type of test that can be performed without doing a teardown. Even with a tear downn, how does one know what stall convertor is in the car?

good question, no answer except to foot brake it until it breaks loose on YOUR motor. This is sometimes called the stall speed, the flash speed is when you punch it and the motor winds up and then the convertor kicks in (harder to determine, but usually different as the flash is higher) Buyer beware on stated stall speeds. As its known, same convertor will stall at different speeds behind different torque motors and flash will change with weight.