50 were built http://www.ehow.com/list_7383614_1968-dodge-dart-specs.html
Although racers like Dick Landy and Don Garlits had modified Darts in the mid-60s to run in the NHRA Funny Car class using the 426 Hemi, Super Stock class racing of the Dart was almost non-existent due to the small V-8s available. In 1968, Dodge contracted Hurst Performance to build a limited number of 440 in³ V8-wedge and 426 Hemi-powered Darts to compete in the SS/B class as the LO23 Hurst Hemi Dart.
Dart body shells were shipped to Hurst who would install a magnesium cross ram-inducted 426 Hemi into the engine bay, facilitated by sledge hammer hits to the fender wells to make room for the Hemi's installation. The rear wheel well arches were also modified in the same manner the shock towers were modified up front. Fiberglass nose, fenders and hood, lightened bumpers, no side view mirrors, radio and heater delete, no soundproofing in the floor and firewall, no back seat, a trunk-mounted battery, acid dipped doors, belt straps for window cranks, Lexan windows, and Dodge A100 van seats mounted on drilled seat rails for decreased weight.
When shipped to a dealership, a Hemi Dart had a disclaimer on the window stating "Warning: this Super Stock vehicle is to be shipped on the bottom level only of all rail and truck transportation"; this was to ensure that the Hemi's low-hanging oil pan would not get damaged and keep the fiberglass nose from being damaged on any low-hanging obstacles.
These cars would successfully cover the quarter mile with elapsed times in the ten second range. According to Chrysler staff engineer Larry Shepard, the majority of these Darts were Hemi powered, all though a small pilot run of fifty 440-powered Darts were also built in 1968, in 1969, over 600 were built with thte 440
Would you believe one of these was found with only 33 miles on it? Well, maybe one was, but the story was that one of these was raced once, put in the garage. Guy passed away and his kids inherited a 12.5:1 dual quad race hemi with open headers. Nice car to inherit huh?! Well it didn't happen, someone was pulling the wool on MoparMuscle and told them a tall tale. No idea why, but they wrote it up anyway http://www.moparmusclemagazine.com/featuredvehicles/mopp_0208_1968_dodge_dart_hemi_super_stock/index.html