How to get a good ground in your Mopar

Welds fail? Car fall apart?.
I hadn't worked on the Duster for 20 years, Installed a rear sub frame and trunk battery, grounded to new sub frame. Tried to fire it up; had forgot firewall to engine ground, smoked the ground at the heater. Installed a 10 from the firewall to engine. Went to the front of the engine, installed a battery cable to the k frame. Nice, now.