7.25 sure grip

I assume you are talking about a bodies here!
Almost all slant 6 cars came with a 7 1/4'' rear end, and sure grip was an option. They are not common, i have yet to see one and i've owned/seen a lot of these cars with the 7 1/4.
Yes, they did in fact have the 5 on 4.5 big bolt pattern axles in them starting in '73. It must come in a car that had disc brakes from the factory.
As a rule of thumb, all a bodies had small bolt pattern '72 and older.
'73 and up, you got big bolt pattern discs and rear end if you ordered power brakes or a v8. All 340 and 360 cars came with disc brakes and a 8 1/4'' rear. The slant sixes and 318's could have had a bbp 7 1/4 or a bbp 8 1/4.
So....if you ordered power brakes on a slant 6 car, it automatically came with the bbp disc brakes and a bbp rear end, more than likely a 7 1/4.
If you ordered a slant 6 car without power brakes, you got small bolt pattern everything and 9'' drum brakes from '73 to '76.
If you ordered a 318 car, it automatically came with the bbp disc brakes and rear end power or not, and could have came with a 7 1/4 or a 8 1/4.
Sure grip was optional on all cars, and they are most commonly found in performance cars like the 340 and 360 cars, high option cars, heavy duty and fleet vehicles, or northern cars that see a lot of winter.
I hope this helps you.