64 1/2 had beveled headlight buckets in inside edges because lip of hood was not folded over like on 65s. The rad support had 3 cooling holes on generator side, they had non movable seat tracks, gauge cluster had gen instead of alt warming light. Headliner was different moon skin material, the D code 289 4 barrel was only offed in first 6 months which if you were lucky to find one was a dead giveaway. True all were titled as 65s they ran the first run with these oddities until the end of May. I restored and sold an April 17 built D code 4 speed 64 1/2 coupe in prarie bronze with black interior a few yrs ago so I know the subject : ). I also know how hard some of the parts are to find. The headlight buckets are costly. 25 bucks for a 65/6 bucket and up to 400 for a 64 1/2 bucket. Thank god I only needed one!