stu I do not have the original engine in mine either... The engine that was in the truck when my grandmother had it in the late 50's had a blank engine serial number, so I figured it was the second engine in it...
The dealers used to stamp the engine serial number on replacement engines, but in my case they did not.. Most of the time when these old trucks needed a different engine the owners just put one in it and called it a day and did not worry about telling the DMV...
My truck fell off the DMV register so I had to have CHP officer come out and inspect it so I could get it re registered... So in case you have it on non opt do a inquiry to keep it on the DMV register or you have to get it inspected by a peace officer or the DMV... You can do this on their website...
As for AAA, they most likely will mainly be concerned with it being safe for the road and possibly the replacement value if you decide to have full coverage... If you have a want to know call them up and ask what is entailed in their inspection... I can ask my wife about it, she was a claims adjuster for AAA for 23 years...
