CAT 3406B Cam interchangeability

I have what I believe to be an 8PN CAT 3406B. No data tags on the engine, anywhere so it's a true mystery.

I need a cam and am told the OR3787 is the cam I need. Having trouble finding it and wondering what other part numbers will interchange.

My other question is that the OR3787 appears to be for a 310HP engine and not the 425HP. So what makes the 310 a 310 and a 425 a 425, just the cam or the cam, crank and injection pump?

 

That's what I was afraid of, ouch!

HP wise is this cam the same for the 310 and the 425? Better yet any way to figure out exactly what I've got without having to run it on the dyno?

Seems to pull like an old Schneider cab-over even after a fresh rebuild.

 

Posted over there as well.

The C is electrically controlled and the B is all mechanical, right? This one is definitely all mechanical, BIG cone on the front of the timing cover.

 

Many possibilities for sure. thanks for the info!