small bolt pattern ?? how ?

What year is your car? All of the A bodies through 72 had the small 4" bolt pattern. MOST of the 73 & later cars had the 4 1/2" bolt pattern but there seems to be some drum brake cars that still had the 4" pattern. If you have a 73 or later disc brake car it would've come with the 4.5" pattern. 72 was also the last year of the 8 3/4" rear in an A body. So, if you find an A body 8 3/4" rear it will have the small bolt pattern. 73 they switched to the 8 1/4" rear. The 7 1/4" rears can have either pattern, depending on the year of the car. All of this refers to unmodified stuff. Somebody could have swapped parts.