Welcome to FTE. There are a few places to find it actually. One being on the edge of the drivers side door opening. The other is on the passanger frame rail between the front axle and the firewall. It will be stamped and over time dirt and paint fill in the stamping so you can't see it that well.
Any one know where I can find the vin# on my 1963 ford f-100?
Welcome to FTE
Two possible locations: Either on the inside of the glove box door (early 1963's), or on the left door face near the latch.
The number is also stamped on the top of the right frame rail in front of the cab.
The VIN is what your truck is registered with. It should be on the title.
Door VIN's: It sometimes doesn't match what's on the registration. 1961/66 doors are all the same, and due to damage, some ppl swapped doors, and forget to change the Warranty Plate...where the VIN is located.
slight correction to Bills post above...the fit/function of the doors are same 61-6 as mentioned, but the body line is straight on the unibody trucks and have the drop down area on the 64-6 doors if Im not mistaken...Im not for sure on the non unibody 61-3 trucks though...minor detail though if its a work truck.