1962 C10 heater question..

[primetime62]

Hello all, new here...I own a 62 C10 longbed and recently repainted the heater box and wanted to put it back in...let me back up, I bought the truck back in June and the guy gave me a box of parts..the heater was inside..has two switches, one is fan and the other defrost...I painted it but haven't checked to see if the motor, resister, switches work, or if the core leaks..I bought the 1960 shop manual hoping it would show how to intall, but not alot of info for the side under the hood..My truck has a rebuilt 350 with a T5 tranny..I noticed to box holes have covers and plugs..would love to know what needs done to get her going..Will post pics soon!