I have a 66 coronet, and i need to replace the leaf springs, can anyone tell me what cars or trucks have compatible springs? I have searched the local scrap yards for b bodies with no luck, just wanted to know if anything else will work.

There were several leaf packs that could have been used on your car. You can look in a '66 parts book to see which ones. Generally a spring that has been cycled excessively or overloaded is not really a good choice for continued use. If you do get used, then look 'em over for signs of failure, then load them up (stand on 'em is one way - but do hold on to something get on and off!) and measure the deflection. Then calculate the spring rate of each. If left and right are not the same - one or both is worn out. If they are OK, you can rebuild with new interleafs and bushings.

This company has some information posted

http://www.stengelbros.com/DodgeCarLeafSprings.htm
the link was posted in this thread
https://board.moparts.org/ubbthreads/showflat.php?Number=7193764
which you may find some it helpful

I looked at current ones and both sides are 5 1/2. Wanted to upgrade as i plan or drag racing. I know there are shops around here that custom make springs, i was thinking 7 leaves on passenger and 6 on driver. thanks for the web site, i got the measurements and will hit up some junk yards to see if i can find a good set.

Drag racing would necessitate biased springs, if you want to drive it more, go with the same number of leafs on them and use cal tracks. ESPO or JR spring will ship them for a reasonable price. Tim

Have a look at the Firm Feel site. It will show lengths and types. I'm pretty sure there are lots of later cars that will interchange. I'm believe the late B/E stuff will work but not sure on the early B's.

You have lots of choices. If your current springs aren't broken/cracked, low budget but time consuming would be to buy a used set, disassemble and remove the main spring. Cut the ends off the donor main spring and simply add another full leaf to your current spring pack. A spring shop or several vendors will have the spring bolts and clamps you need.

Alternatively, take your current springs to a spring shop and have them add a leaf. This service is about $150 in my area.

If you want to start new, the MP extra heavy duty spring uses a bias design. I started with a set of the MP springs from Firm Feel. These springs are by design flat and spring rate was a little low for my application so I got a leaf added by the spring shop. I like the result.

Finally, Firm Feel, "Springs and Things" and other vendors can select or make a spring for your application.

There is more to leaf springs than simply leaf counts and arch.

If you are building a dedicated drag car, I'd recommend you call Mancini and get the appropriate front hanger and the accompanying correctly rated SS springs packs. Mopar engineering put a lot of research and design into that set up that will allow you to simply bolt them in and concentrate on tuning your combo rather than chasing potential issues with spring set ups.