From Tiny
Quote: "FYI, if your truck is titled by the engine number, putting the later model engine in will leave your truck without the title number anywhere on it. If this is the case you will save any future owner a huge headache trying to title the truck by re-titling it yourself after the swap. Just contact your state DMV for their process in getting the new numbers on your title."
This is great information. I'm going to run into this problem soon and was wondering what to do about it.