The "misfit" tank destroyers are a series of more obscure designs that could fit an hypothetical fifth tank destroyer tree in WOT.
These designs are much more likely to ever appear as premium tanks rather than as part of a regular tree, so they will be treated separately.
One of the most obscure STUG III variants is the design project of mounting an 88mm cannon on its chassis.
Such a powerful weapon would have made the STUG even more versatile as the larger caliber gun would have been extremely useful both against tanks and softer targets thanks to the heavier HE shell.
The concept reached wooden model stage and as seen from the picture, would have required a redesigned superstructure and likely made the tank itself heavier:
How would the tank behave in WOT?
Baby Jagdpanther II comes into mind.
Good alpha although not stellar penetration for its tier, coupled with a fairly mobile chassis.
Depending on superstructure armor (would it be 50mm or the heavier 80mm? I'd go for tier V premium with 50mm and decent mobility) it could also be fairly mobile but given it would be slightly taller than the base chassis camo would suffer a bit.
Now, would you like to see this tank as a tier V premium or as a regular tank?