Need help changing heat core

Need help changing heat core on 86, 1/2 ton with A/C is there any web site, books or good advice. How hard is it to change.

Been a few years since I have done one that old. I do remember that in order to get the heater box off, there is a bolt on the bottom of the box that will require the inner fender well to come out. OR, you can try cutting a hole with a sawzall.

i had to replace the one in my 87 and it wasent all that hard. it does require lowering the inner fender on the passenger side. i have a haynes manual for my truck and it walked me through the process with no prob. it took me about an hour in my driveway.