94 gt engine question

I'm not really sure where you could just look at your engine and tell. A lot of parts have a date on them. I just took off my throttle body for example, and it had something like 3/6/95 on it. Maybe this will help. Do you have a reason to believe it is not the original engine in the car or something?
 
Well, when i got the car the dip stick that was in it Didn't read the right amount of oil. So I went up to ford and order a new one. When I recieve the dip stick. I had trouble put it in. Just as hard as the older dip stick I had. So, I was woundering if anyone knows about the casting number or any number that I could find on the engine that would tell me when the engine was born. Because, I think the engine came form another car.
Thanks, Michael