I just backflushed the heater core and lifted my front end in the air, topped off my coolant, and got all the bubbles out of my truck while running the heat on high. Its nice and hot now. My temp gauge still reads cold but I think it's a bad sensor giving my a false reading

 

I worked at garage who's owner spent a while working in a rad shop, and he told me that what makes older Chryslers have such good heat, also makes them have bad heat.

OEM Mopar heater cores are fantastic for pumping out a lot of heat because of their design.
Unfortunately that same design means they clog easily. This is usually why people have problems.

For anyone else with a "no heat in my older mopar" kinda issue...

1) Get a "real" coolant flush done, in both directions, at a skilled shop with a flush gun. (it's a rad shop tool that attaches to the tool air line and a water supply) If used correctly it fully cleans your cooling system. If used incorrectly it can damage your heater core by making it round-ish instead of a rectangle, due to pressure.
2) make sure they don't flush though the heater control valve. A rad flush gun will damage it.
3) Install a new thermostat.

Hope this helps those in this year's deep freeze.

EDIT: Mac Tools makes an awesome funnel kit for filling cooling systems. It extends above the motor and has a bunch of adapters. You simply keep the funnel full, with the engine running, until the bubbles are gone. You then put the included stopper in the funnel and dump the extra into the overflow tank and top the overflow up. The funnel kit is awesome for a lot of other things as long as you clean it. Paid $40 in Canada. Probably $3.99 in the USA. hehe

 

Ok boys, thanks! I'll try heater core flush. Like I said, I had new water pump, thermostat, put on, still cold as a well digger's butt.