Hello All!

Hoping one or more of you kind experts can answer a few questions regarding 1966 Cutlass and 442 stock rear coil springs.

1) What is the relaxed height (inches) of the standard rear Cutlass springs?

2) What are the differences between stock and heavy duty rear coil springs?
Height?
Coil thickness?
Both?

3) Did 1966 442 models offer both standard and heavy duty springs or only heavy duty?

4) Are the 1966 upper rear frame spring pockets the same for both standard and heavy duty springs or were there two distinct/different frames options available for Cutlass and 442 package option models?

5) Are standard and/or heavy duty 1966 rear coil springs interchangeable with any other year Cutlass/442/GM A-Body (I am aware '67 springs are pigtailed at both ends).

Thanks in advance for any info you can provide.

Stay safe and well!