The GMC CCKW

hello
here a newbie with the first question

I found a gmc engine and I like to know the year and for what car it was used
there is a plate with the number 270370465
the same number is stamped in the engine
I found out it was used in a cckw but was it also used in a dukw
and what is the date it was build
thanks

jan

Jan I have here only this information(by Ron Dettling).
year 46-52....engine 270....block casting number....2135412....head casting number....2136477 to 2193417
year 53........engine 270....block casting number....2135412....head casting number....2194819
year 54........engine 270....block casting number....2135412....head casting number....2194819
year 55-63....engine 270....block casting number....2324003....head casting number....2194819.

Please note the head casting numbers:

From 1953 onward they (according to the casting numbers presented here) had the head with the bigger ports that was made for the flat topped pistons. The earlier engines (WW2 thru 1952) had the turbo topped pistons. The later ones had the flat pistons. DO NOT MIX THE HEADS!

The block didn't care which pistons were used, either would fit. The head does...

The bigger ports are part of the reason the later engines had more hp: WW2 = 94 hp Big ports = 140 hp

The different block casting number for the last group was I believe for the change to the side motor mounts. If you try to put one of these, or the last series 302 cid engine in a CCKW/DUKW, you have to take the cam shaft out with everything that that entails: (cam shaft, timing gears, oil pump, distributor, fuel pump, rocker arms, push rods, lifters)to put a plate with the front motor mount foot back on

thank you for the usefull information