73 dart swinger front end wont stay aligned???

i have done 3 alignments on this car in the past 2 months all three times leaving the front specs as follows caster = 3.6+ camber = .5- toe = .00-.05+ identical on both sides. i have also replaced all bushings in the front end, tires all the way around, pitman and idler arm, new tie rods and sleeves, readjusted the worm gear tight as hell, and i will be installing a set of bilstein shocks this weekend :-)

any advice as to why the front end is not staying aligned?

also any advice on what offset i should use for a 73 dodge dart swinger im thinking 17'' american racing torque thrust powder blacks?