1971 Big Block Exhaust Manifolds???????

[71CHEVYSHORTBED402]

Seeking an education please. EDIT: EDUCATED. The variable is for A.I.R., not air conditioning.

I was looking into fitting the heat shield for the stove pipe for the 402. Out of curiosity, I took note of the exhaust manifolds, which are (LH 3994045) and (RH 353030). First off, the truck is stock A/C. I just never put it back on with a engine rebuild long ago, but I plan on re-assembling. So here's where the fun begins. Take a peak at this here Wiki link, right out of the Light Truck Parts Catalog (below).

First, I don't believe they put a 396 in a 1971 Chevy (402 replaced the 396). Second, they don't show a 402 (aka 400) for the 1971, but they do for a 1972............They also don't differentiate between exhaust manifolds (A/C and not) within the grid for 1971.

If that wasn't confusing enough, if I go by the 1971 396, then my LH exhaust manifold is correct (assuming A/C doesn't matter), but the RH manifold is incorrect. If I go by the 1972 400, then the LH exhaust manifold is incorrect for A/C, but the RH is correct for A/C.

WTH? With all this mess in mind, safe to say the A/C cannot be mounted properly with one of these exhaust manifolds?

For the record, the heads on this 402 came off of a 396. I'm way to green to know if that matters for this application, though I suspect it doesn't. The LH exhaust manifold had to be replaced with the engine rebuild.

HELP!

http://www.t.gmpartswiki.com/getbigpage?pageid=21508