heaters aren't covered in the shop manual, they'd be in an accessory install manual - not "hard", just take it a step at a time, remove the heater from the truck, disassemble it on the bench, get the core checked at a rad shop
"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir "When we tug a single thing on an old truck, we find it falls off" ~ me Some TF series details & TF heater pics
