Editing GMC V8 engine (section)

==GMC engines==
GMC's own V8 was the {{convert|637|CID|L|1|adj=on}} unit, which was essentially a 478 [[V6 engine|V6]] with two cylinders added. It shared the {{convert|5.125x3.86|in|mm|abbr=on}} bore and stroke and used a single [[camshaft]]. It was manufactured in gasoline and diesel versions, and was the largest-displacement production gasoline V8 ever made for highway trucks. The GMC 637 V8 was produced from 1965 to 1973.<ref>{{Cite web |date=23 March 2017 |title=Now Here's a Big Block: GM's 637 Cubic-Inch V8 |url=https://www.macsmotorcitygarage.com/now-heres-a-big-block-gms-637-cubic-inch-v8/}}</ref>