Different Heater Boxes

The firewall will be different with any model non a/c box. 73 and later uses a totally different controller but so does the non a/c controller for pre 73 ( you have push buttons now ). Some moding req'd no matter which way you turn.
I would prefer the earlier non a/c box and controller just because its all mechanical, no vacuum required. Controller and bezel for that should be easy enough to find. Good luck
Ok appreciate you letting me know! I did buy the mechanical linkage off eBay the other day bc I knew it was different but I didn't know that other stuff so I'll continue to look for an older style Hester box and do some work to make it fit appreciate it!