Well that's always been my thought too, but since we other Autobots manning weapons (Blaster's tower is very similar) maybe it's not?
When it comes to assumptions, I always figured any of the 1984/85 Autobots we didn't see in season 3 was there... and died. The mausoleum ship in Dark Awakening is fairly large.
It's only in the collected edition, and it's not much better than a fanfic explanation really, but it's there. And you can see a scan here: http://tfwiki.net/wiki/File:TAM_TPB_Gestalt_Fight.jpg
This has made me wonder if the current G1 collection will have a volume that includes both the Marvel and IDW adapations of TFTM. Doesn't seem to be a place for it though.