The Stovebolt Site Forums The Shop Area Engine Shop What do these #'s mean?

I have a 1958 450 GMC ( Pictures posted in the gallery.) I'm slowly pulling the nose off to work on the engine ( distributor don't move when engine turns & you cant turn the distributor by hand ) No big loss pulling the nose off even if it's a minor fix on the engine. I want to get behind all the tin & fix/undercoat as I go. Been soaking all the bolts with a cotton ball soaked in Kroil for a few days & so far everything has come apart easily/no breakage. Back to my question about numbers.. Mooching around in the cab I found a sticker saying the engine had been partially replaced & to use Part # 2345853 when ordering parts. Does this number mean anything to anyone? I'm proceeding under the idea this engine is a 302 in line 6 cylinder & I want to run it. If the engine in the truck is no longer a 302 I have a line on a fine running International school bus with a 345 & Allison Automatic transmission....

GMC sixes don't lie. There is a flat horizontal boss just behind the distributor with a serial number punched onto it. The first 3 numbers give you the size, most likely a 270 or 302, but could have been changed for a 261 chebby motor. It is also possible, but not probable given the size of your beast that the motor is one of the larger gmc sixes that got as big as 503 cubic inches.

THANKS Bidbadswingdaddy. Right alongside the distributor under some dirt was the boss simply stamped "302" no serial number. Now at least I'm sure of what I have & which direction to proceed. I guess this means some one put in a possibly new GM shortblock?

If the only number stamped behind the distributor is a "302", then this is a factory replacement 302 cubic inch engine.

Where are you located? I am near Albany and have a 54/55 GMC 350 COE (with a 270 replacement engine).

Yup! That is a factory replacement motor. I am using one of those in my truck.