A bit more thread necromancy, but I was trying to recreate the entire USCM arsenal as listed in the Colonial Marine Technical Manual (including the various tanks they have) and I figured I'd search to see if anyone else has done work on this.
It's good to know I'm not alone in being frustrated by the fact that I couldn't make the dropship a proper 35 tons. However, there's a few things here I think are worth mentioning.
When unloaded, the UD-4L is supposed to be able to withstand +6g, so the SI needs to at least hit 6 to represent capabilities, resulting in a 6/9 thrust profile, not 4/6. The description of the GAU-113/B suggests an autocannon of some kind, LAC/2 seems a good fit.
Has anyone stated out the M577 APC versions? Like the M577A1, M577A2, M577A3, M579, or M201 MLRS? Or the tanks and SPG, like the M242A2 SPG, M34A2 Longstreet Light Tank, M22A3 Jackson Medium Tank, or M40 Ridgeway Heavy Tank?
The Technical Manual also mentions a UD-24 dropship that's supposed to enter service sometime in the 2180s (ALIENS takes place in the 2170s) with a 70,000 kg lift capacity. There's also mention early in chapter 3 of the AD-19C/D Bearcat and AD-17A Cougar strikeships, UD-22 Navajo gunship, and the CS-14 Briareos heavy lift shuttle; the shuttle is probably how the really heavy USCM equipment like the M40 Ridgeway gets planetside.