JHS,
It gets kind of complicated. If a plant is producing more than one model, such as coupe, convertible, sedan, etc., each body style will have it's own consecutive numbering from Fisher on the cowl tag. The VIN of course is assigned to a chassis in the order of final assembly, no matter which body style winds up on that chassis. There is a correllation of course, but not one where a "difference" in both numbers should be any certain value.
The best way to determine if one number agrees with the other would be to find a known original car built early in production and one late in production. Take the difference in body numbers and the difference in sequential VINs and plot both on the same time line. Then when you find a car with a VIN somewhere within that range, an approximate "expected" body number can be derived. You'd need to plot those production lines for each body style.
Again, it's only an approximation, since the rate of production of one style or another may vary, such as more convertibles in the Spring, etc.
Hope this helps...
Verne
