Baldwin/Motion 70 Chevelle?

[Mr70]

I saw a 1970 LS-6 Chevelle at a carshow recently.It had a Hone Overdrive unit in it.The car was fully restored,but the owner said he left that Hone unit in it.He had no idea what a Baldwin/Motion car was,but did say the car was full of after market Hi-perf accessories from the 70's.
So did the Hone Overdrive unit only come on B/M cars,or could it have been bought at a parts store in the 70's as well?
How could I document it to be an actual B/M Chevelle if it ever was?
Or could it be a "Day 2 car".