where can i get heavy duty springs similar to the F250 for my 150 4x4??

 

I drove a 95 Chev 1/2 ton and carried a large fuel tank on back for a few years, and the leafs were a bit worn out, so we had a local truck repair shop make new ones, and add an extra leaf, it hauled the weight great. I think if you ask around a few truck shops such as a Freightliner garage or something similiar they should be able to make you new springs equal to a F250