Bob, I've seen two distinctly different designs of rocker arms used on GMC engines. One type appears to be either cast or forged, and look almost like Chevy rockers. The other type is obviously assembled from multiple pieces of stamped steel spot-welded together, with a rounded pad at the tip that contacts the valve stem. I'm not familiar enough with GMC engine variations to know if there's any rhyme or reason about which type of rocker was used on any specific engine. I'd have no problem with refacing the one-pierce rockers- - - -not so sure about the assembled ones!

Here's an example of the stamped steel GMC rockers - - - -not sure how long the Ebay auction will be there, and yes, moderators, I understand why posting links like this are discouraged. I'll go ahead and slap my own wrists!

https://www.ebay.com/itm/1939-1941-40-1946-GMC-Pickup-Truck-228-248-270-302-Rocker-Arm-Shaft-Tappets/113838395870?hash=item1a814c11de:g:wYQAAOSwlk1dQgft

Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!