74 duster pulls to the left, then centers, HELP!

Frankly, mismatched, crap tires could be 99% of your trouble.

I can still remember one winter when "I was poor" (well, moreso than I am now) I thought I could 'get by' putting some recap bias ply snow tires on the back, after all---I was only going to use it "around town, right?" Had radials on the front, these recap bias on the back

At 25-35 mph, I thought that darn thing was gonna waltz right off the road. It was incredible -- incredibly bad, that is.