I've got a (guessing) mid-80's model Toyota 4 cylinder 5 ton gasoline forklift. Damaged the battery, realized the regulator was putting out 20 volts. The problem is that the info plate on the front is long-gone, and was told a serial number might be under the battery on the side, but not seeing anything there. So no way to identify what model. I'm finding 4 versions of regulators, all look similar with a 2-row 3-pin connector.

My question, is there much difference between the various models? Pinout changes? Or just 'updates' and higher/lower amp versions? Should I just get one & cross my fingers?