The coolant is low, probably from a leak. You need to have it checked with a pressure testor.
I wouldn't think you could flush a heater core. you can flush a radiator. Heater core you would have to replace if it is leaking or stopped up
Was the gasket replaced? Have you checked the hose and the heater core. Is everything tightened down?
I would like to Know of any recalls on a 1994 dodge dakota?
Have you checked for leaks? also the cooling fan may not be working.
Pressure test system to determine the origination of leak i.e. hose, radiator, heater core, etc.
If they are Automatics it will not shift properly. It would bolt up if they are the same engine.
No.
This would indicate that the system is low on coolant when the gauge is hot. Not enough coolant to service the heater core.
your blower motor has gone bad In the firewall on the passenger side of the truck is the blower motor speed resister coils, they burn out alot. I could not find one for my Dakota so I got one from a dodge caravan and I changed the wirring, that is the most likely problem
Old age
After about 1995 all Dakota flywheels would have sensor targets on them.
IT would be possible, but it would be easier to buy a 1988 or newer Dakota and have it already equipped that way.