69 Z Leaf springs
 

Steves thread on coils was close but I'm having a rear leaf issue I believe I think this pic says it all. Rear Leafs were replaced with repro Z springs from Camaro specialties 15+ years ago. I took some rough measurements of LR= 24.5" RR= 26 ". Now front coils? no idea if ever replaced or not but its the back that's noticeable most I do have a new set of the Moog 6308 springs and I'm not sure where to start - replace fronts and retest my thought if its the same would be to swap rears from side to side? One thing I did notice is why I can see more of the right side of the gas tank VS the left. Maybe this a body issue?

The right exhaust pipe also hangs lower. I'd be looking at the trunk pan and frame rails.

It looks like the lower valence is pushed up slightly on pass side, and bulged down on drivers side unless its just the picture, that would explain why the gas tank looks not the same.

Is the front end the same side to side ? Check your rear subframe bushings…

car doesn't appear to have been hit in back badly ever tail pan was replaced due to some thick mud like 1/4"

that's what my son thought too

Fronts were measured at LF= 24.5" and RF= 24 3/4"
front subframe bushings were replaced with Urethane 20 some years ago

the car did lave LR quarter and tailpan replaced at least 20 years ago

If you scroll down slowly, you can see the whole car leans to the left (even up at the roofline). The gas tank, tailpipes and tires appear to be the only things level. Once you level the suspension, the gas tank and tailpipes will probably need to be adjusted.

Before you go replacing your rear springs, try going to a spring place where they might be able to rebow and straighten that drivers spring to match the other side.