[nebk10]

Going to try to bring some life back to this one... First of all, thanks for the excellent write-up! Wish I had found this before I took on this project with my 86 K10. A couple questions on replacement parts... Any idea where I can find the black clip in the third pic?
Also, I was thinking the rod for the flapper popped out of the heater box... I ended up breaking the housing trying to pop it out instead of appropriately sliding it out.

It's looking like the junkyard is about the only place I am going to find a new heater box... Does anyone know some super-secret place the sells them new? I'm at my wits hunting for a new one.

Originally Posted by 85gmcguy

First picture shows approximate location of the studs sticking through the firewall (arrows). Second picture shows actual studs on removed heater box. Upper left circle shows heater hose connectors. Please note- the heater hoses MUST be removed, they will not come through the firewall. (Ask me how I know). The white arrow is the "heater blend actuator". This is the new one. Should give you an idea of how tight to the firewall it really is. The cable from the dash control that operates the heat flapper must also be disconnected (picture 3).

Originally Posted by 85gmcguy

The heater box splits into two pieces. The plate (1) mounts the HOT/COLD cable, and is held by three screws. The mixer door is held in by and pivots on a pin (2) which must be removed. Note the position of the flat "tang" on the end, it only goes back in one way. The pin in the fourth picture goes through the end of the "blend door actuator". The circled screws in photo five are under a foam seal which must be removed to access them. Keep it to put back on. The rest of the screws are easy enough to find, remove them all. The last pictures shows the halves being separated.