1950 GMC Cannonball

Written by Daniel Strohl
October 20th, 2007

I have a thing for GM’s cab-over trucks from the Advanced Design era, particularly the 1.5-tonners 2-tonners, but when I spotted this Cannonball by the side of the road just west of town last week, I had to stop.

Actually, I’d seen it in the guy’s yard ever since I moved up here, but never had reason to stop and check it out until now. Unlike the 1.5-ton 2-ton COEs, the 520 Series Cannonball was an out-and-out over-the-road tractor, much taller and larger and rated at – I believe – 2.5 tons. This one in particular’s a 1950, fitted with a gas-burning 360-cu.in. six-cylinder engine. From a quick glance at the engine, it doesn’t appear to be of the same architecture as the smaller Stovebolt gas engines GM used at the time.

The Cannonball was in real good shape, though. No rust to speak of, and the seller said he’s had it running and on the road for the last 10 years.

I don’t really need something more spine-jarring than my one-ton – and at $9,500, I won’t be buying this particular example any time soon – but a 1.5-ton 2-ton Advanced Design COE I’d jump at.

Rob English says:
Dan, I think the owner might possibly have his engine facts jumbled a bit: if this truck is still in its original configuration, it would have a 318 inline six cylinder engine. Like all GMC truck engines from ‘39 on, this 318 (and the 360 too if this is a replacment motor) cubic inch inline six has full pressure (60 psi) oiling, insert bearings, and was engineered to be beaten and flogged at maximum throttle (governor) all in a day’s work.

Nice piece. This cab is the larger style COE cab (there were two styles) and is a manly truck for sure. I would imagine with the stumpy and bouncy 121″ wheelbase, you might need a note from your kidneys before you buy this one.

The key to GMC’s is the chassis serial number as show on the ID Plate, also called a Caution Plate, and mounted on the driver’s door hingpost:
HFR 521 007

H = 1950-1951
F = Cab Over Engine
R = Tractor
52 = 520 series
1 = 121″ wheelbase
007 = this was the 7th 520 series COE off the Pontiac production line in the 1950 production run.