The FSM also calls for Chrysler Rust Resistor and soft water in warm climate, as well as 190 skirted tstat.

While on the topic of coolant, the 70-72 FSM says 70-71 use 7psi cap and have simple overflow, but after Nov 1 1972 use a 16lb cap and a closed reservoir.
Since I added a reservoir can I use a 16 cap, or are there other pressure considerations? FSM says to keep pressure under 20psi when cleaning or testing, for all models...