Editing GMC straight-6 engine (section)

{{Infobox automobile engine
| name = GMC straight-6 engine
| image = 
| image_size = 
| alt = 
| caption = 
| manufacturer = [[General Motors]]
| designer =
| aka =
| production = 1939–1962
| configuration = [[straight-6]]
| displacement = {{convert|228-503|CID|L|1|abbr=on}}
| bore =
| stroke =
| block = cast iron
| head = cast iron
| valvetrain = [[Overhead valve engine|OHV]], 2 valves per cylinder
| timing = 
| compression = 
| idle = 
| redline = 
| operating principle = 
| supercharger = 
| turbocharger = 
| turboboostpressure = 
| fuelsystem = [[Carburetor]]
| management = 
| fueltype = [[Gasoline]]
| oilsystem = 
| coolingsystem = [[Water-cooled]]
| power = 
| specpower = 
| torque = 
| length = 
| width = 
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| diameter = 
| weight = 
| emissions level = 
| emissions control = 
| predecessor =[[Buick Straight-6 engine]]<br>[[Pontiac straight-6 engine#Flathead Six|223 cu in Pontiac straight-6]]<br>[[Oldsmobile straight-6 engine#230|230 cu in Oldsmobile straight-6]]
| successor = [[Oldsmobile V8 engine#324|324 cu in Oldsmobile V8]]<br>[[GMC V6 engine]]<br>[[Chevrolet Turbo-Thrift engine]]
}}

The '''GMC straight-6 engine''' was a series of [[gasoline]]-powered [[straight-six engine]]s introduced in the 1939 [[Model year#Automobiles|model year]] by the [[GMC (automobile)|GMC Trucks]] division of [[General Motors]]. Prior to the introduction of this new engine design GMC trucks had been powered by straight-six engines designed by the [[Buick]], [[Pontiac (automobile)|Pontiac]] and [[Oldsmobile]] divisions of GM.

The new engine family featured a [[Overhead valve engine|valve-in-head]] design, pioneered by Buick and also used by the [[Chevrolet]] division's contemporary [[Chevrolet Stovebolt engine|"Stovebolt Six" engine]]. Many [[engine displacement|displacements]] were produced using three [[Engine block|block]] sizes: "Group 1" (small), "Group 2" (mid-size) and "Group 3" (large).<ref name="meyer"/>{{rp|15}}

The straight-6 engine was replaced by the [[GMC V6 engine]] in 1960, remaining in use only in certain light-duty models of the P-series [[Multi-stop truck|step van]] until 1962.<ref name="meyer"/>{{rp|pages=27–28}}