I know they are supposed to look like the stock ls1 manifold but is there anything that you can distinguish a LS6 and LS1 manifold by? and I know that 01-02 are supposed to have them, but is there any 98-00 that came with them? thanks

 

No.
As far as distinguishing charactaristics, I'm not sure.

 

I don't believe any 98-00 came with them. As far as a distinguishing characteristic, the lack of the EGR inlet behind the TB is a definitive sign.

 

Well, I think you can get LS6 intakes with the EGR input now - not sure if you could get the LS1 intake without it, but I'd imagine you could.

I think the floor/bottom of the intakes are different - one is flat, and one is not - couldn't tell you which was which though...
good luck
Shane

 

yes u can get ls1 intake without egr......and the way to tell is to look at the part number....

 

another way is coolant plugs in the front of the intake.it might just be me but an ls6 looks like it has bigger runners or higher rise to it.