DMT Mopar Heater Box Rebuild / Restoration Gasket Sets & Gaskets

Heater box restoration kits contain all the seals, foams, caulks, etc necessary when restoring a heater box. Most kits come in two sizes

Basic Kit - containing the basic seals, foams and caulks

Big Kit -  which contains any additional items that we offer for the specific heater box like screw kits, new rubber blower motor cooling tube, new firewall grommets, heater box clips sets, etc.

E Body AC Heater Box Rebuild Tech Info
Link to a great step by step rebuild of an E Body AC heater box. 71-74 B body AC heater boxes are nearly identical so this helpful info would be the same.
https://forum.e-bodies.org/interior/6/ac-heater-box-rebuild/667/