I picked up a replacement engine for my 216, it was in a 56 GMC 1/2 ton truck the seller didn't know if it was original or was replaced at some time. Block casting # 3836340 Light Blue color. Serial # on the lower block # W 23 206 and close to the distributor # 34784 Head casting # 3836848 Looking through the info online and on here it looks like it's a 261 with a higher compression head. What I would like to know is if my research is correct. Thanks for any information anyone can provide.
The same block casting number 3836340 was used on both US and Canadian 261 from 1955-62 as referenced in Bolter tclederman's Stovebolt Casting Numbers webpage and many other resources.
Sounds like your truck is in for a big step up in the powertrain!
~ Dan 1951 Chevy 3 window 3100 Follow this story in the DITY Gallery "My Grandpa Carl's Truck and How it Became Mine" 1966 Chevelle (Wife's Hot Rod) | 2013 Chevy Silverado (Current daily driver) US Army MSG Retired (1977-1998) | Com Fac Maint Lead Tech Retired (1998-2021)
I have 1957 and 1959 261 engines from Canadian GMC trucks both stamped serial numbers start with a "W". The "M" inside the raised square on the right side of the engine indicates it was cast in Canada by McKinnon industries and the captains bar indicate a 261 engine. Solid lifters its a truck, hydraulic lifters for a Pontiac.
