Cushman, Ric at PMD does sell an aftermarket walking beam suspension kit for the Wedico trucks. It's made by a company called Osswald, and is listed here -
http://www.gardentrucking.com/produc...esort=1&max=10
It is designed to bolt right up to a stock chassis. You won't need to drill any holes, but there have been some changes to the design of the suspension through the years. I purchased my first Osswald suspension kit about 6 years ago. Then I bought another 2 or 3 years after, and to my disappointment, the design was changed. In my opinion, the changes made the kit worse then the orignals, as the bolsters that the spring packs pivot on got longer, which really kind of makes the Wedico trucks sit higher in the rear, after installing them. If you want something better, consider Scale Art's swing spring suspension. It's pretty much the same thing, but better.
http://www.scaleart-shop.de/Axle-Sus...rame::723.html
My Wedico has the older style Osswald rear suspension on it, which is the best design from Osswald, but for the next Wedico I build, I will go with Scale Art's suspension. If you are interested to know the differences in the Osswald kits, I can get you some photos. I have both the old and new style.