Congrats on the purchase!
The 3:27's were an option on the GT. Most people will tell you 3:73's will be the way to go. That's what I plan on installing next year. I've driven a 97 with 3:73's and it felt great and didn't really sacrifice highway rpm's at all. You'll have opinions on both sides but 3:73's really wake everything up for the $400 or so you'll spend.
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66 Tahoe Turquoise Coupe
Laser Red 96GT Ragtop
Both are slow but easy on the eyes!