blower motor question

[gman]

I've done a search on past posts but I'm still uncertain about the answer to my question. My blower fan starter whistling last night when I turn the fan on. I assume its the blower motor. My question is do I get this out from the engine side of the firewall, passenger side? I'd swear thats what my service manual said when I read it. But reading some of the past posts, I'm confused. Not sure if I need to get under the dash to get it out also. How difficult is this going to be? '72, 350, 4x4, fact ac. I get heat, not all that hot but I think I have a bad thermostat that needs replacing too. Any tips or things to avoid? Whats the proper way to do this? Is it absolutely necessary to remove hinge on pass side? Should I replace heater fan at the same time? If so, is that in same area as blower motor? Do I need to replace core? I think I'll open up the heater and duct work to see what goodies I find in there. Any help appreciated.