need help with a booster bracket

[s102000]

This is my 2nd post and I already need some help..On my 69 GMC, I don't think the brake booster bracket on the fire wall is original to the truck...It has a 72 front end with disc brakes...The elder friend I bought the truck from can't remember what year the bracket came from or if it is the original, seems he told me a long time ago that the booster came from a car..So I'm hoping you guys can help..

I'm needing to buy a new booster, so I went to autozone and ordered one (booster, mc combo) for a 72...I looked on their website and the part number for the booster is the same from 69 to 72 but the booster will not line up with the mounting holes on the bracket..

The two top horizontal holes on the top of the bracket measure 3 3/8" hole to hole...The booster mounting studs measure 3 3/4" center of stud to center...The vertical studs, holes line up..Thanks for any help..