Matt -residual valve and prop valve not required for the dual reservoir drum/drum master cylinder setup. Here's a link that may help, based on Chief Rocka's thread here -
http://67-72chevytrucks.com/vboard/s...d.php?t=487384 When you go disk/drum, then you can buy a disk/drum (unequal) dual reservoir master cyl and the prop and residual valve. I'm not certain about whether or not you'll need the residual valve in either setup though - I always thought the res valve was only if you had a "low" mounted master cylinder. With a firewall mount, I do not believe it's necessary - but let's get that confirmed by someone on here. But for the drum/drum - you don't need either as long as the master is on the firewall, that much is correct.