My manual shows R43 Plugs for this 1971454 ci 365 HP. I have R44 Plugs installed. What if any problems might this cause???? Anyone out there have advice ???? Thanks Runamuck 

If you are driving at low rpm and short trips, the 44 will actually work better.  They have greater antifoul properties due to a hotter plug surface.   That's what the number is, the heat range.  They also help combat a bit of an oil fouling problem through worn valve seals or rings, if you have that problem.

But for extended driving or repeated hard accelleration, I would NOT recommend them.  The extra heat on the surface of the plug could cause detonation (pinging) and require a higer octane fuel to control.  You may not notice the ping, but you could still have a bit.  Detonation over a long period of time, or strong detonation can damage engine components.  In severe cases it can cause burned valves and create piston erosion failure.