Hi Rick,
You may want check on inter-changability.
If your G38 has the skinny iron prop hub, i don't think the carbs can be switched because the small holes may not line-up between the newer WT 338 and the old style G38 carb flange. It will bolt on, but the small holes may not line-up. The newer style G38 has the larger aluminum prop hub with the WT 338 carb.