Aug said: Yeppers! Fender used nitrocellulose lacquer until close to the 70's, after that, they only used it on the headstocks because the decals didn't mesh well with the poly. Nitro clear has a really bad habit (or good depending on how you look at it) of changing colors. In the earliest years, the Mustangs only came in 3 colors: red, white and blue. We know these colors today as Dakota Red, Olympic White and Daphne Blue. Anyway, the nitro clears turn yellow over the years, thus changing the color, hence the confusion. On a slight sidenote, Reranch offers a really bad tinted clear if you're gonna attempt to copy that "yellowing" effect.
100% correct Aug, Fender did not use Sonic Blue on any early mustangs, the colours were red, white & blue. Fender did not want to let the secret out, that they were using custom colours on student models hence the red, white & blue tag, the colours were really as Aug stated - on any other guitar these would have carried an upgrade price. The clear nitro also caused some odd purple bursts to comp blue mustangs & odd copper bursts to comp candy apple red mustangs, these are often misleadingly called rare & are not, as it is only the aging process of the nitro clear coat.
The same sort of secret was applied to the early 80's USA Bullet, that had standard telecaster necks & Vintage hardware, they also used a variety of tuners from vintage Kuson's, "F" tuners & standard Fender stamped tuners, also strat pickups - all parts found on strats & tele's on a student model !
That's the way Fender's business brains worked - economical with the truth !