[mbgmike]

Good. most all GM spacing on master cylinders are
3.3/8"
3.1/4"
3.1/8"
Some of the new replacement mc's are slotted instead of round holes to allow to fit most applications. The factory were not. Most of the disc/disc were 3.3/8" We do brakes for a living so we can get the correct combo. Pic's worth a thousand words.