I read that link as indicating the standard generator for a heavy duty truck as 948R, with the 934F as an R.P.O (regular production option). And, the standard heavy duty truck has no voltage regulator, which means it would have a voltage cutout only. The asterix in the R.P.O. box takes you to the bottom of the page which indicates you could get a voltage regulator with current control. Bottom line is you have more choices to keep it "correct". Kent
