Well , there is not a lot of difference. You know about the timing chain and the cj is gears, But to me I like the cj2 better than the ww2 engine, I think they were build better, I know folks who has the cj in there ww2 jeep and they having less problem. I,m working on a m38a1, but will use the cj f head and 12 volt system. I got 4 cj flat heads engine . I don,t know about the m38 engine, never had one. I would sell the gpw engine , use that money for a later cj engine or m38. Also try g503 they know there jeeps. Try to find engine local , shipping nowday is out of sight. I got 3 halftracks, a ww2 5 ton tractor and jeeps and cckw ,
too much junk