I had posted earlier about little or almost no heat in my 70 Challenger 440. Well I started with the obvious, changed the thermostat, no improvement, flushed the heater core , no improvement, replaced the heater core problem fixed. Here is the surprise, I decided to cut the "old" (which turned out to be new) core open to look inside. When I cut the tanks off the one with the inlet and outlet tubes in it I found the problem. The inlet tube was jammed all the way to the rear of the tank thus not allowing but a small amount of water to enter the core. The core itself was clean with not obstructions. This was just a defective core. Just thought I would let you guys know.