Well all I can say is.... replace the fronts with 24's, put 30/30 maxis on the rear.. As far as auto slack adjusters go, on the rears you may have a hard time finding ones that will mount to the s-cam. I tried to do this to 2/ 86 RW's, and I couldnt find a parts guy that new how to cross the Mack numbers. the left and right are different. and the s-cam on the left side was too short ( by about 1/4") to allow a modern ambidextrous slack adjuster to be secured with the snap ring at the slack adjuster.. this being said,,, I am not 'all knowing' there may be a good auto slack out there that works. We just put the manual slacks back on and maintain proper adjustment,,,, just like in the olden days.. and with that being said... you can adjust your brakes to perform the way you need them too, and be safe and legal... I welcome all opinions and corrections about my posting... jojo