Greetings . . .

I think they only used Pontiac for one year perhaps two. From what I've read GMC had traditionally only only built big trucks 1-ton and larger. They got into light trucks starting in '36. They chose the long stroke (4 1/8) Olds flathead. In '36 the bore was 3 5/16 for a displacement of 213. Olds increased the bore in '37 to 3 7/16 for a displacement of 229. I believe this engine was base offering through 1940.

In '38 they used the Pontiac flathead (a 223 I think). I read somewhere that this engine was option in '39 as well but my Chilton's flatrate only shows tune up specs for this engine associated with GMC in 1938.

In '39 GMC introduced it's own flathead in 1-1/2 ton AC-250 line. Not sure if they ever put that engine in a pickup.

Really a question for jummy specialist - I'm just a spectator.

regards,
stock49

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