Once everything is hooked up and adjusted, feed the studs and the heater core inlet/outlet through the firewall. I used my trusty helper (arrow) to hold it in place till I could get the nuts started on the studs. Make a last check to be sure nothing is between the heater box and firewall before you tighten it up. Attach your heater hoses and anything else you disconnected and you're good to go. Duct work installation is reverse of removal.
