The "M8A2" was the name of the model file and I'm not sure where the modeler got that name because his description was of the regular M8. There was a 'Block II Thunderbolt' envisioned with 120mm main gun in addition to other changes, but there weren't any prototypes made.
There were several light tank variants as part of the Armored Gun System competition like the Stingray, which is used by the Royal Thai army; CCVL, which became the M8; Expeditionary tank, etc. Maybe somewhere in there was an "M8A2". And, even though the program was cancelled in the '90's there's been some renewed interest in it lately.
I suppose this is 'what if' unit and more modern than original M8, what fits perfect within my mod.
