Brake Booster has two studs - Master cylinder has 4 holes

I have found that my brake booster has two studs for the master cylinder to mount to it. The new master cylinder has four holes to be mounted. I have triple checked the new master cyl. part number for my 69 Barracuda and it seems to be correct. So now I am guessing my brake booster is wrong for the car.
Do I have a different year brake booster on the car?
Any info will help.
Thanks