@USCDOC13 posted:Time to button it up!
With all the beautiful installation work and custom fabrication of the new firewall cover, I think you would want to get rid of the manual heater shutoff valves, which will require removing the interior panel and firewall cover to open or close, and replace them with an electric valve so you merely hit a switch on or under your dash.
Here's the Thermotion 354-69494 that someone else on this list installed: https://www.amazon.com/Thermot...69494/dp/B07119TY9Y/
Available for less at: https://www.truckac.com/heater...354-69494-t4037.html
And even LESS EXPENSIVE direct from Thermotion: https://www.thermotion.com/4-p...l-valve-pn-354-69694
I'm thinking of installing one of these myself.
Following are some other inexpensive electric heater bypass valves. Note that I have NOT verified if the ports on the following valves are sized correctly for our heater hoses.
4-port valve from a Cadillac: https://www.1aauto.com/chevrol...hcx00004/535137/1997
Or a pair of these from a Ford F-350: https://www.amazon.com/KarPart...495AB/dp/B09HY2PBW9/
This looks like a generic version of the same thing: https://www.amazon.com/Four-Se...Valve/dp/B001TPSXDG/