Heater box (fan, core, control valve) pulled from my own '73. Was working fine, I think the core was replaced at some point before I got it cause it looks really clean. I replaced the heater control valve and the short hose to the core shortly before I took this out (hose is not oem but I found one from a Fox body Mustang that fit without kinking), valve still works back and forth easily by hand. Blower motor was strong at the high speed. Only reason I took this out is because I'm adapting a heating /cooling system from a Frontier.
$75 - probably the wrong time of year to try and sell a heater box, but avoid the Christmas rush !