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Front Passenger Side
David Kennedy
| Contributor
Posted October 27, 2004
Photographers: Ken Brubaker

Street-Legal Chevy for Any Kind of Throttle-Driven Competition

Absolutely unstoppable. It doesn't matter if it's mud bogging in Bloomsburg, sand drags at the local quarry, ice racing on Lake George, or even street driving, Jim Otis' '74 K10 powers its way to the top anywhere that throttle rules. Ever since he bought it in 1978 as a toy to romp through southern Florida mud, Jim has been building this 1/2-ton to burn and churn through the deepest goo and has now spread his wings to compete in burnout contests. Jim's truck does everything fast--and is guaranteed to get you to the grocery store and back between commercials because this thing is still street legal.

Engine:Stock Mark IV 502 with 930-cfm Predator carb and 250hp NOS kit
Transfer case:NP203
Front Axle:Dana 60 with 4.56 gears and an open differential
Rear Axle:Dana 60 from a {{{Ford F-250}}} with 4.56 gears and a Detroit Locker, 35-spline Moser shafts, and Strange bearing caps
Lift:12-inch Superlift springs. Dual shocks up front, no shocks out back (Jim never got around to installing them)
Tires:39.5x18-16.5 Boggers (street tires)


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  • Don't let the clean body fool you. This '74 Chevrolet has spent more time in the mud than a pampered Hollywood actress. When the driver-side door fell off due to a rusted hinge, Jim replaced the entire body with new sheetmetal before bathing it in a splash of Sekins paint.

  • After 9 years of thrashing, the GM Performance Parts Mark IV 502 just keeps coming back for more. Jim's never been nice to the 8.75:1 motor and has been surprised by how well the thing has lasted, considering how many times he's hit it with the 250hp shot of nitrous and the wide open throttle of the 930-cfm Predator carb in the mud and occasionally on the street. The engine's not pretty, but it has never given Jim any problems and has kept him surprisingly competitive in all six classes of mud racing.

  • Yes, ladies and gentlemen, that is an NP203 transfer case bolted to a Turbo Hydra-Matic 400 transmission. Jim's '74 Chevy originally came from the factory with the rare SM465/NP203 combination to pick gears behind the 350 small-block. But when Jim went to big-block 502 power straight from Tonawanda, New York (not too far from Jim's house, we might add), out came the four-speed and in went the TH400. The whole transmission swap cost him $4,000 even though Jim lets his mechanic date his sister.

  • Jim found that the ultimate traction differential for the front of his mud truck is a stone-axe-reliable open Dana 60 differential with 4.56 gears. He used to run an ARB air locker up front but surprisingly enough found that it would pull him left and right under hard throttle more than it would pull him straight ahead. Now Jim relies on the scooped paddle tires out back and massive wheel speed to propel him down the track.

  • Class 6 mud racing pits Jim against the nastiest 2,000-pound mud boggers on the planet. In a field where paddle tires and custom-cut 39.5 Boggers scream through the goo, Jim's 6,000-pound machine has held its own as the only truck in the country to compete in all six classes--running a best time of 4.3 seconds down the 200-foot track.