<VV> 65-66 differences

[aeroned at aol.com]

I'm getting interested (or obsessing) in figuring out more about my Corvairs and when they were produced and have a question. My 66 coupe has a 65 nose bar and heater box (it has the small box that goes into the rear inlet area). I've always assumed that this was an indication that the car was rebodied at some time in its past. The VIN and body tag indicate that it is a 66. The body tag has a build date of the 4th week of Jan (01D). Could it be possible that they were still using 65 heater boxes in Jan? The nose sheet metal could have been replaced. The hidden VIN is buried under undercoating that's in very good condition. Is there any other ways to determine if the body is a 65 or a 66?
 
Ned