There’s a new thunderbolt in town, as of last year (2019) with the release of Record Sheets Succession Wars. MUL doesn’t say who uses (or more likely used) it, but given it’s called the -5D I’d guess it has a Davion connection. Apparently it was introduced at the tail end of 1SW, and was probably popular with the same nutbars berserks who thought the Shadowhawk -2d was a good idea.
It has the usual solid Thunderbolt armour. The missile rack is a ten tube, with a single ton of ammo. It’s at this point things stop being like other Thunderbolts. The second gun, in the opposite torso, is an AC/20, and that’s the full extent of its weapons. Ten rounds mean you can’t try many shots on bad numbers, but is certainly enough to keep you as a threat in being for a while.
So if you’ve got two hundred BV at the end of force building, you can now upgrade your Hunchback to something with back armour and a long range token. It doesn't have backups, but the hands are free for punching; there’s that at least.
TLDR: it isn't a Thunderbolt, it's a chubby Hunchback or baby Cyclops.