5kTQ Master Cylinder

["L. Scott Oliver" <SOLIVER@gcwf.com>]

I'm having the master replaced and the brake lines upgraded to braided
metal.  Turns out the (apparently original) master cylinder on this 87 5kTQ
(sedan) is the part for '86-88 wagons only (with the heavy duty rear
brakes): 447-611-021 with the 25mm bore.  I'm putting in what I thought
would be the right replacement, 443-611-021with 23mm bore.

Two questions:  First, what exactly is the difference in the wagon heavy
duty braking package?  Vented rear rotors?  Two, does anyone think it
makes any difference to go to the smaller bore?  Anyone else with a
sedan gone through this?

TIA,

--Scott