thanks for the reply.i got lucky and drilled to .105 pretty much centered,so i tapped to 6-32 per a post i found here.i searched before posting too.but if any one has any tips or suggestions on this 7044213 carb,id like to hear them,instead of making another post. went and looked at the 66 truck its going in and found its a small block 400,ebrock intake,headers,dual exhaust,not sure on cam,heads are stock iron.