I have two thermoquad carbs on the way. On is a 77 vintage for a 400BB/727. The second is an 84 360/727 according to the snippets of info scattered around the web.

Going by model year with the parts store none of the carter p/n's of course match anything their listing shows. For what little I can find there is 77 and earlier and 78 and later are the cutoff years for these carbs. Of course looking on a few sites listings they call out one p/n as covering everything... so WTH is it?

By picture most of these kits come with several different versions of the same gaskets to cover variations and both primary sizes so I wonder if it really matters ?

I'm at work right now so I dont have the carb #'s handy or I would share.

Where you get your kit from makes a difference. Some places have everything in one kit, while other places may have more then one kit available, which is carb number dependent. I bought a Thermoquad kit from O'rilley's once that only had one needle & seat in it. I could buy the second needle & seat separately if I wanted it, for extra money. That kit only had the gaskets I needed, nothing extra. The last kit I bought, from NAPA, had all kinds of extra stuff in it, but they still needed a number, even though they only listed one kit, according to the counter guy. Gene
Gene

It is better if you provide the carb #. Some of the carbs have a lot of extra stuff attached (depending on year)for altitude, clean burn, or what ever.
Here's a few web pages that might help you (the last one has a good list of the carb #'s when you scroll down) with parts, and kits.
Good luck.
http://www.carburetion.com/Carter4TQ.htm
http://quadrajetparts.com/carter-carburetor-parts-carter-thermo-quad-parts-c-299_158.html
http://www.carbkitsource.com/carbs/tech/Carter/pages/tqguide-Vaanth.html