My 2002 Dakota had the radiator replaced a few years ago along with replacing the hoses. The radiator cap on the new top hose is rated at 20 psi. While most manufacturers say a 4.7 should take a 20psi cap, there are also a lot of comments on line saying the factory spec is 14-18 psi and the proper cap should be a 16 psi. I notice listings saying there were 285 and 287 4.7L engines. Could the factory rec cal for 16 psi on some year models and 20 psi on others?

1998 to 2000 was 14-18 psi 2001 up 18-22 psi due to cooling system changes.

Thanks a bunch. I like a definitive answer and now I know there is a difference and why there is a difference. Much appreciated.

21 PSI for my 03 quad cab with heavy duty cooling (tow pkg).

Personal opinion -> i feel if 12-14lb caps were used, instead of 19lb caps, maybe heater cores would last longer. but thats just my personal opinion and not based in fact at all.
Personal experience-> 2004 3.7 in winter running a 13lb cap, my heater core that had a slight seeping is now unnoticeable and the coolant level remains constant. Heat output is fine. Maybe its the lower pressure cap resulting in an early pressure release and overflow, maybe its the new radiator and high flow thermostat, who knows.

Lower pressure in the system is also going to lower the boiling point of the coolant.

I believe most heater cores fail due to coolant issues. Mixing tap water or improper coolant, etc. That either clogs it, or eats it from the inside out.

I run 30%water 70% coolant, never had an issue with over heating or boiling away,