Project 1974 Chevy K5 Blazer - Building A Premudder

Last year's yellow Ultimate Adventure Chevy saw more beatings than any other U.A. vehicle to date. It was so wasted that there became a point where it was smarter to part it out to make multiple vehicles work rather than dumping a ton of money into it. Since this Blazer was being built with as much stuff as I could find already laying in my yard, it was lucky enough to be the recipient of the yellow U.A. Chevy's front Dynatrac Pro Rock 60, crossover steering, and Redneck ram. That front setup lasted through the extreme beating given to the yellow Chevy, and it would all swap straight onto my Blazer, even the leaf springs.

Arrington bored out the hole where the shackle hanger mounts to the frame. The rivets were knocked out of the factory ones, and they were ditched to make room for a new pair of Off Road Design heavy-duty shackle hangers with more durable urethane bushings and larger hardware. The new ORD shackle hangers bolt up to the frame without too much headache. The biggest issue is probably trying to get the rivets out of the stock ones and off the frame. Usually I would've just used ORD's shackles, but since I somehow left those off the order sheet, Fabworx quickly made up almost identical shackles to hang our springs from.

The '73-'87 Chevys have a clearance issue with crossover steering and the factory frame crossmember below the engine. Since this K5 was going to be getting the crossover steering from last year's UA truck, and we had pulled out the engine, Arrington knocked out the factory crossmember to get this Off Road Design motor mount and custom tubular crossmember to fit in between the framerails. This will help us clear our steering, while still providing lots of structural support. The motor mount/crossmember package fixes the steering clearance issue while also providing beefy motor mounts to replace the worn-out factory ones.

The crossmember and motor mounts attach much the same as the factory one would. If you have an opportunity to remove the rivets while the engine is out of your frame, please do so as the extra room and visibility make it a much easier job than trying to suspend the engine from a cherry picker while you remove the motor mounts, and then try to replant it.

I knew beforehand that I wanted this K5 to be motivated by a big-block, and I had thought it was a lucky coincidence I had found a K5 with a 396ci big-block. We were about to tear into the engine to try and weasel some serious horsepower out of the existing short-block using a trailer full of Edelbrock, Performance Distributors, and Flowmaster parts.

The engine was already sitting on an engine stand, and the heads came off the 396ci big-block after twisting some crusty old bolts out of the heads. Arrington had already warned us that it wasn't a good idea to put all these high-performance parts that would generate more heat and pressure onto a tired old block. Well, Arrington had raised a very good point, and it was a decision I didn't even have the chance to make upon examination of the No. 1 piston. There was a good-sized hole right on the ring land of the piston.

The Dynatrac front axle was already complete and proven off road, but we needed to drop down from last year's 5.13 gear ratio to a 4.88 gear that I preferred, especially with a big-block that could make up for less gear. Yukon Gears were stuffed around the ARB Air Locker and the Pro Rock was buttoned back up. In the rear, a van-width 14-bolt (3 inches wider than the 3/4-ton truck axle) had become a likely candidate, so a Yukon Gear spool and 4.88 gear setup were packed into the axle by Fenzel. What we had here is one of the first versions of the Yukon Gear spool, and the one you will order comes as a solid ring at the gear instead of being scalloped like ours was.

Fenzel used an indicator to get just the right setup when he dropped the spool and gearset into the 14-bolt axle. The spool will not only be the lightest differential (or lack thereof) we could put in the axle, but will also allow the most fluid capacity, and generate the least amount of heat as there is no spin differentiation between the two axles. Spools are great off road and very predictable, but they get tiresome on road and are almost unbearable (on road).

Once Fenzel had the axle completed, he used an inch-pound torque wrench to check how much drag is in the setup. Once he was happy with it, the axle was filled with gear oil. When installing a new ring-and-pinion, it's best to drive it for 20 minutes, and then let it cool down completely to allow the gears to break in correctly and provide the longest, most reliable life. You should do this three times as well.

We handed the axle over to Forrest Moore once it was ready for the four-link. Moore starting mocking up some plates that he would later weld to the centersection to mount the upper triangulated part of the four-link rear suspension.

Orange County Transmissions had just finished giving a TH400 tranny a complete B&M parts overhaul while adding in a few of its own tricks for this truck (Turbo 400 Revival, p. 68). I hauled it up to Santa Rosa, California, to the Fabworx shop where Arrington added the new B&M torque converter and flexplate. We made sure to swap the output shaft because we were going from an NP205 output to an NP203 output, as this K5 was receiving the Off Road Design NP203/NP205 doubler kit.

The ORD doubler kit and transfer cases were also proven parts from last year's yellow U.A. Chevy. They had done great behind the Ramjet small-block and TH350. Now I was about to see if they'd hold up just as well in back of a serious big-block and TH400 tranny