The crate GM 355 has standard factory exhaust manifolds. I recently picked up a pair of ramhorns for a SBC. I have finally gotten around to making the switch, but I have a couple of questions?

1. The left hand manifold had a "shelf" built into the front port, what is that for?

2. Where can I locate replacement bolts for the manifold to exhaust pipe flange? Also where can I locate bolts to secure it to the block?

3. The right hand manifold came with a spacer where the exhaust pipe ties in, is that needed or can I not use it?

The ramhorns I purchased



My engine with its current exhaust manifold

 

The "shelf" is an alternator mount and shorter studs are available from just about any auto parts store and the spacer is not needed.  It's a replacement for an exhaust flapper valve used in northern climates to aid in engine warm up.  Just make sure you have a good seat in the exhaust manifold for the exhaust donut.