Building A Premudder - Big Block Chevy Engine & Four Link Suspension Install

A Performance Distributors D.U.I. (Davis Unified Ignition) system was put in place of the original '74 junk. The D.U.I. is the easiest ignition to work with. With it you get a much bigger, hotter spark and there's just one wire to hook up to a switched-ignition positive lead. The only other wire connection is a single wire to a tachometer. We were also able to try out a Performance Distributors Mr. Amp 130-amp alternator. It's a one-wire hookup as well, and simplifies and improves our electrical system even further.

For the rear four-link, we used QA1 1x1 1/4-inch spherical bearing rod ends for the lower control links, and 3/4x7/8-inch ones for the top links. The QA1 rod ends feature a one-piece body that is more durable in heavy-duty applications such as dragging 1-ton axles over rocks. For the actual links, we used big 2-inch by 0.250-wall tubing for the lower ones that would be hitting rocks, and 1 1/2-inch by 0.375-wall for the upper links.

We originally intended to use Off Road Design's new four-link kit. It triangulates the lower links and keeps the upper links parallel with the frame, and includes an over-axle all-inclusive crossmember and link, a coilover mount, and a front square-tube crossmember (shown) that sends the lower links out at a reverse triangle. But as universal as this kit is for many fullsize truck frames, there is an interference issue with the lower reinforcement boxes below the body on '73-'75 Blazers.

Once we realized that the O.R.D. kit would not work for us, Fabworx built its signature dual-triangulated four-link. The company's four-link uses traditional upper triangulated links that meet above the rear axle pumpkin and attach to a bracketry housing that Forrest created. The lower links are a reverse-triangulated design that mount the lower links at the ends of the axletubes and come together at a front crossmember set in back of the transfer case and below the frame. In actuality, the crossmember that Fabworx makes for its design is so similar to the one supplied with the O.R.D. kit that we were able to use the O.R.D. one.

Fabworx created some nice frame brackets that attach the upper links to the frame. The 1/4-inch plate was used for all brackets that Bryan and Forrest designed, and though these obviously require extensive welding skills, Fabworx is looking into redesigning its bracketry to make a kit that anyone can purchase.

Forrest used cardboard to first mock up all the pieces he wanted Dave to cut. Dave is paying his dues as the second youngest at the shop, and as such gets to cut stenciled parts out of sheetmetal so Forrest can weld them up.

Once all the pieces were cut to form around the 14-bolt pumpkin, Forrest began welding them on. There is some dispute in our industry over the strength of welds done straight to the iron of an axle centersection, but we've never seen any problem with it if properly welded, and neither has Fabworx. On top of this housing, two link brackets will point symmetrically at about a 35-degree angle from the truck frame. When we reconvene in Part 3, the guys at Fabworx will be up to their ears in D.O.M. tube and even less happy with me than they were when I showed up with the dilapidated K5.