That must be a heavy truck or really worn out springs! My '37 had nine leafs in the rear stack (1.75" wide) and was so stiff it would not bounce, even with original worn out springs. I removed 4 leafs and added teflon liner just to get it to move.
Are you sure the springs you have are for a truck?
How about a leaf spring set up using coil over shocks. The leafs hold the axle in place and the coil overs hold the weight. All it would require is a good solid mounted crossmember on top.
Joe
