The actual stall speed/rpm of a convertor varies depending on the motor combination. IE the same convertor will flash to a different rpm behind a stock 340 small block, than behind a high torque big block. My suggestion would be as follows: if you currently know your engine combination, rear gear, and tire size, send this convertor to a reputable convertor company. (TCI/ATI/Coan or others) They can cut your convertor open and tune it for your setup, as well as make sure it is ok and worth the effort. Also bear in mind, all convertors are not created equal. This process should be cheaper than new, and you will know what you have in the end.