[Joe's Garage]

The 1972 crossover is not reproduced.

A 1971 exhaust crossover won't work correctly on 7F6 heads, or on any other 1972-up heads. You'll have a huge exhaust leak unless you block the exhaust ports of use some type of adaptor/shield.

The main difference is that on the 1972 crossover, both of the exhaust crossover ports are smaller.

The 1969-71 crossover is small on one side and large on the other. The heads have enough meat around the crossover ports that the gaskets will seal.

The 1972-up heads have a 2nd opening above the exhaust crossovers that doesn't normally need to be sealed. If you use the early crossover on later heads the gasket is not able to seal both openings.