AMC Bellhousing ID?

Dan, the AMC 327 isn't a Hudson design either, it's an AMC design. It was introduced in mid 1956 model year as a 250 in the Hudson Hornet Special and Nash Ambassador Special (actually the smaller Wasp and Statesman two door hardtops with Hornet/Ambo trim). It was for all practical purposes a clean slate design. The main design engineer came over from Kaiser and had worked on a Kaiser V-8 design (actually built a prototype) and he brought his experience over to AMC. I'm sure there are some design elements from the Kaiser design in the Gen1 AMC V-8 (56-66 250/287/327), but it was designed in-house at AMC (AMC formed in 1954 as a merger between Nash and Hudson).

Just to complete the history lesson, the Gen2 AMC V-8 is the 1966-69 290/343/390, and the Gen3 is the 70-91 304/360/401 (and 1970 only 390).

Some people don't like the "GenX" designation as GM uses a similar nomenclature, but it's just short for "Generation X" and is accurate. There is little difference between the Gen2 and Gen3, but the block and head castings changed. Just a slightly taller deck on the block, different exhaust ports on the head -- but all parts interchange with a few caveats (such as custom piston pin heights for some crank/rod/bore combos). The Gen1 is totally different -- the only commonality between the Gen1 and Gen2/3 is the bore centers. That was done so that the old boring equipment could be used to bore the new block, saving a couple million bucks.