The Navy tended to keep using small boats until they had to be replaced, so older ships had older types of motor whale boats. Newer construction got newer types of boats - maybe. When wartime construction ramped up, and parts were scarce, shipyards often used whatever they had laying around. Newer ships might get older boats. This practice continued through the Vietnam era.
You need to find photos of the ships boats you want to odel to determine what Mark/Mod they were (and this isn't always easy to determine because motor whaleboats look like motor whaleboats).
If you want detailed drawings (construction blueprints) of several different types of motor whale boats look at this post:
viewtopic.php?f=52&t=155093Phil