From the get-go, I'd never once considered keeping anything stock beneath Dirty's sheetmetal other than the frame, albeit a fairly modified frame at that. As much as I appreciated the added comfort of the rebuilt semi-stock suspension in my '53 3100, it was more an appreciation of a vast improvement over what had previously been trying to keep the ol' truck between the lines without bouncing off everything in its path. The new ride, while nice, tight, and really solid and safe, was still to me quite antiquated, at least as it applied to driving in Southern California. I wouldn't change the '53, but at the same time, I wasn't going to follow the same route with the '39, and for more reasons than just improving the ride quality.
As you've hopefully already witnessed, the first thing that Total Cost Involved did with Dirty was swap the I-beam for a modern IFS. But more than just updating the truck's suspension, TCI also updated its catalog to now include part numbers for the late-`30s GM trucks, something they'd not been able to provide up until now. Following suit, they also developed a full line of rear suspension items for the early 1/2-ton pickups, as well--and not just four-links, either, as you can also obtain a parallel-leaf kit and/or individual components. The four-link kit they offer is available in coilover and air spring versions, and we decided to go the fully adjustable route on this project. Along with substantially improving the ride, I wanted to get the back of Dirty down in the, you know, dirt ... or as close as possible without having to modify the bed floor that much.
Unlike the mid-`50s and later GM truck chassis, these platforms feature a wedge shape, even more so than the Advance Design models. That didn't have much effect on TCI's development of the front or rear setups--in actuality, they ended up going so far as designing "angled" forward link brackets so that the link arms would literally mount perpendicular to the rearend, not inline with the framerails ... in other words, not angled! And while the leaf kit is a bolt-on deal, this application requires a bit of welding. In this case, that included the rear link brackets and airbag mounts to the Currie 9-inch rearend housing; boxing plates and C-notch on the `rails; and finally, the shock and upper `bag crossmembers to the boxed `rails.
All in all, everything worked out for both parties: I got the modern suspension I was looking for, and TCI can now offer it to folks like you over the phone. But this won't be the final installment involving them, fortunately, as we've still got a ways to go, including the part I think many readers will appreciate as much, if not more, than I did--the new brackets to install a side-mount 235 inline-six backed by a Gearstar Turbo 350 mated via a Buffalo Enterprises adapter kit.
