Taken from
www.classicponycars.com , under the History section.
"The 1964½, as it was later called, was available in only two models: the coupe and convertible. Both models featured a lengthened hood and shortened rear deck, chrome wrap-around bumpers, chrome grille with a running horse, and full wheel covers. Both models were available with a 170 cid, 101 horsepower, 6 cylinder engine, a 260-2V, 164 horsepower V-8, a 289-4V, 210 horsepower V-8 and, starting in June, a fire breathing, 4 barrel, solid lifter, 271 horsepower, 289 cid V-8 engine. The buyer had a choice of a 3 speed, 4 speed or automatic transmission, and a variety of rear end gear ratios."
Not sure how accurate the website is but they seemed to know some good information. I've continued to look for a site with "official" information but so far no luck. Sorry guys, hope this helps some.