The vin only has 4 things defined:
model (100-800)
series (D,W etc)
engine (6 cyl, 8 cyl)
plant where built
year is determined by the sequential build number and u have to compare it to a reference list that indicates starting serial number for each yr.
A few other details are listed on the data plate, but are not part of the vin.
The vin is typically on the side of the right frame rail somewhere above or behind the front axle.
Are u sure your truck was a 66? Some states titled them incorrectly, and that was not an uncommon occurance. U would need to know the vin of your original truck to know for sure.
Plastic trucks suck...
Iron trucks rule...