Jerry,
The clay based grease that has been mentioned on this Forum, is used to lubricate the brake calipers only (not slack adjusters) on coaches that are equipped with Meritor ADB brakes (air disc brakes). The only Beaver coaches that are equipped with the Meritor ADB brakes are the Marquis from mid 1998 (start of Magnum chassis production for Marquis) through 2002, and the 2002 Patriot Thunder.
Gerald