The OEM part (casting) numbers for those manifolds is 3704791 and 92. There's a pair for sale on Ebay today for $139.00. Search "Chevy 265 exhaust manifold". The difference is that one of them has a generator bracket mounting boss. Either one will fit on the driver's side head depending on whether or not you want to hang some sort of bracket on it. It works, and the price certainly beats some sort of eye candy that will burn plug wires and turn your under-hood area into a pizza oven!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!