[Dens71TA]

The lower control arms changed(and possible the spring pocket in the frame too) in 1977 as they require different springs. I think they changed again in 1979 when the spindles with the larger wheel bearings were introduced. I noticed my old '81 Trans Am had a much tighter turning circle than my '71 and '73 Trans Ams. The backside of the control arms looks to be more notched.

The center link and tie rods changed around 1975. The best idler arm is the '70-71 style. It uses a bearing. Later styles used a threaded rod and screw up and down as the wheels are turned.