Thank you for the chart "lt1s10". I would have replied sooner, but this is the first chance I have had to log back online, I was on an airplane all day flying home to Ventura CA from Norfolk VA.
My 48 Ford is a pick-up truck and it weighs 3450 lbs total, but I don't know how much the rear weighs. The truck sits very low and rides perfectly the way it is set-up now with me and one passenger. My problem is when I add any additional wieght in the bed or another passenger the rear lowers too much and will bottom out. I was told the way to fix this is to increace the spring rating by 20-30%.
According to the chart you provided I currently have 400 lb rated springs. The coil-over springs are 9 inches long when mounted in the coil over shocks (with now wieght on them) and appox 11.5 inches when not mounted on the shocks.
Based on the chart you provided, I assume I should order the (10 inch #450 W-R) springs. Do you think that correct or will that give me the correcting that I am looking for. Keep in mind that there are four of these coil-overs mounted on the rear-end.
If so do you know where I can order these springs? the ones in most of the catalogues like speedway or Proshocks are only 2 1/2 inches inside diameter the Bilstien sholks I have require 3 inch inside diameter, (same as the stock Jag shocks).
Tim

".......So sanded it all down and resprayed. ......" Been there. done that on a couple of paint jobs over the years. Usually took me a couple of days to get over being mad before I started...
Stude M5 build