How to determin

Hi there Folks: I'm haveing a bit of a problem with a Regulator (12V) its a used but Good model but can't figure out which terminal is B+. I think I have the D+ figured out for it should be beside the DF terminal (D+ is only terminal marked/stamped) This is a F.D. Elecman #240/12-1 if that helps, also when I turn it over to the bottome side it looks to be jumpered from the terminal marked D+ to ? and the other terminal on the output side has two terminals which I think are the B+ terminals but NOT sure. There wasn't any regulator on the bug when I bought it and its been long time sense I've worked with this kind of equipment. Any help would be appriciated. I'd hate to see it up in smoke if hooked up wrong.. LOL