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July 2010 Techline

Wrench Close Up
Willie Worthy | Writer
Posted July 1, 2010

Mishandled Lifted GM, Allison Tranny Swap into an Older GMC, & More!

Where To Write
Address all correspondence to: Techline Four Wheeler, 831 S. Douglas St., El Segundo, CA 90245. You can also reach us by e-mail at; be sure to type the words "Tech Line" in the subject line. All submissions become the property of Four Wheeler, and we reserve the right to edit them for length, accuracy, and clarity. The editorial department also can be reached through the Web site at Due to the volume of mail, electronic and otherwise, we cannot respond to every reader, but we do read everything.

Lifted GM IFS Truck Steering Clunks
I own a '93 3/4-ton Duramax pickup with a lift kit (not sure of the brand, as I bought the truck used with it already installed), and 36-inch tires. The truck handles really badly, wants to wander down the highway a lot, and seems to have a lot of steering play. I had the tires rebalanced and the frontend checked. The shop told me that the idler arms were worn out as well as the steering shafts. I get a "clunk" that I can both feel and hear when I turn the steering wheel. The shop told me that unless I took the tires and lift kit off the new factory steering components would also wear out soon. I see lots of truck with tires this big, so do all of them handle badly, or is there an aftermarket fix?
Mark Hakle

Don't despair, there is a solution. Yes, the bigger tires will cause early wear to all of the steering components, so it would be a good idea to also look at the tie-rod ends. The idler arms have always been a problem with the Chevy trucks once they went to IFS, and not just on lifted trucks. Several aftermarket suspension companies offer a heavy-duty idler arm. From your local auto parts you can order some Moog arms that are considerably strong than the factory units ( For some really heavy-duty versions, check out the ones offered by Super Steer (888/898-3281,

As to the steering shaft, that also seems to be a problem. Chevy has a couple of Technical Service Bulletins on this problem under Numbers 00-02-35-003N and 03-02-36-002. Borgeson ( has a new heavy-duty steering shaft with new U-joints (p/n SKU: 000937) that is far superior to the Chevy shaft, and it's a direct replacement.

Allison HD Tranny for Older GMC?
I have an '88 GMC 3500 dualie with the 454 V-8. Can I bolt on an Allison 1000 transmission to my big-block? Any information would be awesome.
S. Al-Marri
Doha, Qatar

Yes, you can, but it will be an expensive swap. The Allison 1000 is rated to handle up to 620 lb-ft of torque. Initially, it was a five-speed transmission, but a new "Generation 4" 1000 was introduced in 2005 that added a sixth gear at the very top of the ratio ladder, making it a double-overdrive like heavier-duty Allison transmissions. For the 2006 model year, manual gear selection was introduced. This feature gives the driver greater control over the transmission, enhancing operation when more engine braking or less frequent shifting is desired.

The transmission has its own electric controller that also talks with the engine's control module, which presents a real problem when trying to interface it with that of the gas motor. However, there is a solution. Performance Automatic Transmission Center (888/201-2066, ) offers a stand-alone controller and wiring harness for the five-speed version that costs about $1,600. For others reading this, they also make adapters to hook this transmission or any GM transmission to both Cummins and Ford Power Stroke engines. There is also a company called Destroked (303/945-7570, that offers an electric controller as well as special Cummins adapters.

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