[SS Tim]

Dude you are really driving all the way around the block to vist the house next door.
The A.I.R. aka Air Injection Reactor aka air pump was basically an external, belt driven, accessory pump plumbed through a valve and hoses to manifold mounted air pipes. The big difference on the manifolds were the holes to thread the air pipe into at each exhaust port. Often you will find these holes simply plugged.

Again as I stated above A/C is not a factor with this P/N manifold used in this application.

As far as the whole 396/400/402 things goes its mostly marketing. The year breakouts above are correct. The SPID may list a 402 actual as a 396 or 400 so it is always a good idea to verify the engine suffix code if there is any question.