I currently have 12" 200lb. springs on the rear of my 70' Road Runner & need to go lighter to get the shock in the middle of it's travel at ride height. Thinking about switching to 150lb. springs. Car has full interior, steel bumpers, Ladder Bars with narrowed 9". Just curious what other similar B-Bodies are using.......

My 63 Polara and my 64 Belvedere both have used 130Lb. The 63 started with 150lb but hooked better with 130lb.
Doug

Call the shock or spring company of the ones your using now and ask them It seems like on a drag car that the cars work better with weaker rear springs versus stiffer ones I had 170 lbs springs on my street and strip Duster with single adjustable coil overs, I switch to a set of double adjustable(same brand and sizes) with 150 lbs springs and the car 60 ft. better after adjusting the settings on the shocks to full soft on both settings

I run 130# springs on my GTX, but would go to a 150# springs if it was also street driven.

Jeff