bigdog7373: with the setup on a g body, I have to drop the threaded rod through the frame (The opening for the shock absorber bolt) to compress the spring. The threaded rod seems to be about 6 inches too short to allow me to compress all the coils when it's placed in the frame.
68NovaSS: I worry about the soft threads at Home Depot /Lowes as well. Luckily, none of the standard sizes they sell actually fit.
One thought I had was to compress the coil separately from the frame, wrap the coil with a couple ratchet straps, then adjust and compress the coil even more with the spring compressor, then tighten the straps again. when it'll fit between the control arms I would drop the internal spring compressor through the frame, connect it to the compressed coil, attach the spindle, and slowly undo the straps and compressor until the coil is seated in the control arms.