Hey I was wondering if the vin number would be in the same place for my 74 f100 im kind of having an issue as well. if not where on the 74 F100?

 

Yes, it will be in roughly the same location as other year dents.
Like radar457 said, you'll more than likely need a wire wheel on a drill to be able to read it.

 

Where is the warranty plate located? I have put a cab with doors from a 2WD onto a 4WD chassis. What do I need to do to properly title the truck? They are trying to make me apply for a rebuilt title?

 

You need to check with the DMV in your state for the final say, but in most states they go by the VIN that is stamped on the frame. If that's the case in your state then make sure the frame VIN matches the title and either reuse the original warranty plate or you can get a reproduction warranty plate from Kevin Marti Marti Auto Works - Concourse Quality, Hobbyist Price
To answer your question though, the warranty plate is on the rear edge of the driver's door, below the latch assy. Most states don't consider this a VIN plate because it can be easily switched out by swapping doors. To be a legal VIN it needs to be attached to a permanent part of the vehicle.