2001 LS1 or not?
That is not a '01+ engine. That egr gives it away. Forget about the exhaust maniold. Also, look at the casting nubers on the cylinder heads. If they don't read 241 (which was on all 01+ LS1 engines) then you have something previous.
My opinion is that you have a '99-'00 engine with exhaust manifolds of unknown origin.
You need to get them to take them motor back or give you some money alowance back so you can get the LS6 intake and oil pump. Raise hell son! 
My opinion is that you have a '99-'00 engine with exhaust manifolds of unknown origin.
You need to get them to take them motor back or give you some money alowance back so you can get the LS6 intake and oil pump. Raise hell son! 
