I have a 1500 single port headed motor with the dual exhaust (kind of like the old manx style buggies use to have) and it has one extra little tube that bolts on top of the head. I have someone that wants to trade me a stinger exhaust off of a dual port headed motor that doesn't have the little pipe if they will interchange with no problems. My question is will they, is there a block off that goes there or something or are they just plain different.

The tube i believe your talking about is to keep the intake manifold warm in the winter. There is a block off plate they make for that or just wield it shut.