Does any know if C6 Corvette exhaust manifold part # 12603760 & 12603758 will fit on a 1999 LM7 5.3 Vortec motor. Hoping they will mount to the mount, then fit in the CJ8 rail and miss the Novak motor mounts?
Those are the manifolds I used on mine and they worked great. However, I used gen 1 mounts (I had them laying around) and just made a simple adapter plate to bolt to the LS. I haven't seen the Novak ones in person but just looking at the picture of them, I see no reason why they won't work.
On a side note.... If you are going with a manual trans, these are the only manifolds I know of that will work. Most of the other ones I've seen people use dump in the rear right where the slave cylinder is. If you are running an automatic then you have a few more options.
Not sure of the difference, but I’m planning to use 12576061 & 12569388 with the Novak LS motor mounts.
I got lucky and found this set with ceramic coating on eBay for the average price of a junkyard set. I have not mocked them up in the frame yet, so I can’t confirm they will work, but they appear to be the same as used by a couple other forum members.
In regards to the LM7 vs other LS engines, the LS engine line is like the LEGO version of engines (much like the AR rifle platform). You can fairly well pick the parts from most any other LS engine and they will fit (excepting some intake port differences, as well as variable displacement and variable cam advance on some but those can be disabled).
We've used those on a couple LS swaps with the Advanced Adapter motor mounts.
Had to slightly notch the passenger side mount.
Also purchased some exhaust mounting flanges on eBay for them that allow use of the factory gaskets.