72 cutlass supreme, 350 automatic, A/C My driver's side manifold is cracked and need to replace it. Can someone recommend headers that would perfectly fit without any alterations?

 

I don't think those headers exist, as in the best fitting ones still need a slight amount of work for adequate clearance. I have Heddmans on my car and while they fit very well, I had to slightly flatten one tube on the drivers side so the inboard corner of the lower control arm wouldn't contact it at full suspension travel.

 

Thornton makes a new cast iron header that flows more than stock 350 exhaust manifolds. try them.

 

Either the Hedman or Sanderson shorty headers need 0 mods to fit, other than modifying the down pipes to fit on the collector with the stock starter. Use aluminum or copper collector gaskets.

 

As Olds307and403 mentioned:

If you go with the short header such as hedman. The photo below is from my 76 cutlass supreme with 350/350.
With hedman shorties, this type of custom mandrel pipe is likely what you will need to do coming off the driver side header.
I used Remflex graphite header gaskets.



exhaust off header collector.jpg