Snow plow torsion spring upgrade
 

I am going to be installing a snow plow on a 01 f150 Screw cab. I am under the impression that I am supposed to get a pair of #7 torsion springs to replace the stock springs to up the capacity. The question I have is are all of the torsion springs the same dimensions( length, etc) regardless of wheelbase? Also will I still be able to use the same adjusters, etc that are on my old springs? Am I going to have to buy a set of springs for a supercrew only, I hear they may be shorter?
Thank you for any help!