1985 GMC
SQUARE BODYCUMMINS
AN ’85 GMC BODY, A SECOND-GEN CHASSIS, AND A COMPOUND TURBO’D 4BT
BY MIKE MCGLOTHLIN
How many of you spotted your dream truck sitting alongside the highway? When it comes to old iron-especially the classics we grew up with-this method of shopping for a vehicle is more common than you think. Some time ago, Austin Magruder spotted this ’85 GMC, then in two-wheel drive form, while passing through Rolla, Missouri. He promptly inquired about the truck, purchased it, and then spent years roaming all over the Show-Me state in it. Then a friend put his 4B T Cumminspowered step van up for sale and the wheels started turning…
PERFECT TIMING
Luckily for Austin, around the same time he acquired his delivery van, the folks at nearby MCS Midwest Performance Diesel were parting out a second-gen. Not only did Austin buy the ¾-ton chassis, suspension, NV5600, and NP241 transfer case, but he also enlisted their help in making his 4BT square body dream a reality. With a trip up to Brown’s Auto Body, the GMC’s body was flawlessly swapped over to the Dodge chassis and the project was returned to MCS, where months of work would be poured into Austin’s classic creation.
Plucked from an Interstate Battery step van, the 4BT Cummins in Austin Magruder’s ’85 GMC was rebuilt by Keith Summers of MCS Midwest Performance Diesel. With the 4BT’s stock hardware more than capable of handling in excess of 400 hp, nothing crazy was required to ensure the 3.9L remained reliable. The factory crankshaft, original forged-steel (yet micro-polished) connecting rods, overbore OE pistons with dry filmcoated skirts and ceramic-coated tops, and a 188/220 camshaft from Hamilton sums up the extent of the short-block upgrades.