1967 Polara rear wheel cylinder bore ?

[Marcohotrod]

so the original ! right rear (always the first to go) wheel cylinder is leaking . picked up this old 8.75" rear years ago for $75 so do not know if front was drum or disc. any way to know from checking visually externally to know if the bore is 7/8" or 15/16" ? and what is better and I do not think 1/16" is a big deal

 

[slantsixdan]

15/16" is stock. 13/16" is much nicer. All four bore sizes look alike from the outside.