A Tall, Tall Turbodiesel
When we first saw Chris Knaak's '95 GMC Yukon sitting inconspicuously in a lightly traveled area of the Indianapolis Fall Jamboree show grounds we were amazed by the fact that it was sitting on 44-inch tires. That fact alone hinted at the substantial suspension mods that would be required to make the big meats fit. Further investigation revealed that indeed, even in a part of the country where modified fullsized trucks are as common as corn fields, Chris' GMC sports many mods that make it unique.
One of the biggest surprises resides under the hood, where the original 6.5L turbodiesel sits nestled between the framerails. Interestingly, Chris has owned this vehicle since new, and he has piled 287,000 miles on the engine over the course of the past seven years of driving with no major problems to report. The engine is bone stock with the exception of a K&N air filter, but this is where the vehicle's stockness stops, as everything driveline-related, from the engine on back, is modified or custom, beginning with the TH400 transmission. It's been modified by Jet Transmission and now sports a number of go-fast and durability mods, including a B&M manual valvebody. Splitting the power to the differentials is a job handled by a remote-mounted Profab transfer case which features quick-change gears and an aluminum case. With the Yukon's tall suspension lift (we'll get to that in a minute) it was imperative to keep driveline angles as close to factory geometry as possible, so Chris fabbed a transfer case cradle that lowers the Profab unit by a full 12 inches compared to stock. This alleviates wacky driveline angles as the PDL Drivelines-built driveshafts transmit power to the differentials.
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Chris' goal was to fit 44-inch tires, so up front, the stock IFS was removed and a Dana 44 axle from an '85 Blazer was fitted in its place. It rides on Superlift 12-inch-lift leaf springs, and is kept in check with four Bilstein nitrogen shocks with remote reservoirs and two sets of dual steering stabilizers. Chris and his friend Brian Koelling fabbed a new steering setup that consists of a number of custom parts, including a Dodge 6-inch drop pitman arm and a 111/42-inch chrome-moly tie rod with rod ends. The rear diff is a Corporate 10-bolt unit, and it too features 12-inch-lift Superlift springs, but is kept in check with six Rancho shock absorbers. Chris now says that he wishes he'd installed heavier axles-but hey, he's got what he's got, for now, at least. Both differentials are stuffed with 4.88 gears and ARB Air Lockers, and both feature custom 111/44-inch chrome-moly track bars with rod ends that fasten to the transfer case cradle. This massive lift (along with a bit of frame notching to allow for unobstructed lock-to-lock steering) allows room for a set of 44x19.5-15 Super Swamper Boggers on 15x10 Center Line HT Cast II wheels.
To help keep the 44-inch tires from contacting the Yukon's body, a set of Bushwacker cut-out fender flares were installed before the truck was sprayed Victory Red by Matt Petersen at Matt's Auto Body. Other exterior mods include a TrailBlazer roof-mounted lighting system and a 10,000-pound Warn winch. Inside the Yukon, things remain stock with the exception of an eardrum-shattering stereo system that punches out 2,800 watts and includes 12 12-inch subwoofers.
The bottom line is that Chris' diesel-powered Yukon sports a number of creative and unique mods that helped him accomplish the goal he envisioned. Isn't that what truck building is all about?
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|Owner||Chris Knaak, Beecher, Illinois|
|Vehicle model||'95 GMC Yukon|
|Aspiration||Fuel injected, turbocharged,K&N air filter|
|Transmission||TH400, B&M manual valvebody|
|Transfer case||Profab, lowered 12 inches|
|Front||Superlift 12-inch leaf springs, dual Bilstein |
nitrogen with remote reservoir shocks
,four steering stabilizers
|Rear||Superlift 12-inch leaf springs, six |
Rancho RS 9000 shocks
|Front||Dana 44, ARB Air Locker|
|Rear||Corporate 10-bolt, ARB Air Locker|
|Wheels (in.)||15x10 Center Line HT Cast II|
|Tires||44x19.5-15 Super Swamper Boggers|