I cannot ever seem to find the 3 bolt manifold flanges. Local parts stores, muffler shops and junkyards never had any when I was looking for one for a 350. So I figured they def wouldnt have any for a LS1. I need one for a 2000 F body manifold and one for a 6.0 truck motor (I think they are diff sizes). Anywhere online to buy these? thanks

 

I am in need of those as well, anyone know where to get them?

 

The flanges are different side-side on my Camaro and look
like a one-off deal.

I'd suggest picking up some GM gaskets, use them to mark
3/8" mild steel for drill & hole-saw (plasma cutter?) and fab
them up.

Or, you obtain some standard 3- or 4-bolt flanges premade
and weld them up to the castings.

 

Summit Racing has everything you need including the 3 bolt flanges for your exhaust. I know because I just purchased my entire exhaust system with the couplers and flanges at Summit Racing in Reno, NV last week. Hope that helps. I would just call them and tell them what you're looking for.

www.summitracing.com