[indyjps]

Sounds like someone wrecked their hot car and bought a 6 cyl to swap the pieces into.
does the engine / trans / rear dates match up, was the block installed in a car originally or is it an over the counter block, I would think these details could help determine if it was a parted out/ rebuild car if the codes/dates line up to an actual car, if its an over the counter engine it may have been a swap