1 side at a time is what I was told also .the springs I have have the axle nub at 20" like the A-body s/b the springs that are on My Duster know have the axle nub at 22" i include a few pictures to show what I'm dealing with hear the numbers on the spring that is on there know BO 55 then 3722291 and there is a CHRYSLER emblem stamped and the #3485