updated alternator hookup

[Heveyb]

I'm still working on my 250 to 350 engine swap in my 82 C-10 and have got a question on how to hook up the new alternator that came with the crate engine kit I bought. The original alternator (internal regulator) had just three wires hooked up to it...one red one hooked to the post on the back and two (a red and brown wire)going into a plug that plugged into the top of the alternator. The new alternator has the same post on the back but the socket has what appears to be four pins and the new matching pigtail that came with the kit has three wires on it...with one being a heavier guage than the other two. Got any idea on how I should connect the two wires in the current harness plug to the three in this new one?? It looks like Powermaster has an adapter in the summit catalog, part number pwm-140, but I'd just as soon figure out how to wire in the connector I've already got. thanks for any help you guys can come up with.