I have seen people looking for those springs quite often through the years. Best place to advertise them would be on some of the Facebook 47-54 Chevrolet/GMC Truck Groups Pages. That's where I do all my truck parts buying, and selling now. You find just about anything you're looking for, in those groups.

Spanky Hardy
Collector Of Fine Old G.M. COE Trucks & Antique Holmes Wreckers

1948 Chevrolet 5700 COE Holmes HD W35 Wrecker
In the Stovebolt Gallery
More pictures on Photobucket

1950 GMC 250 1-Ton
In the Stovebolt Gallery