Prototype for a new class of runabout. The Yellowstone was designed in 2372 and employs tetryon plasma warp nacelles.

The prototype was existed in the alternate reality and was designed by Ensign Kim. In that reality the prototype was destroyed. It's not clear whether the ship even exists in the actual timeline.

USS Yellowstone NX-74751
   Prototype designed by Ensign Harry Kim in an alternate reality in 2372. The craft lost anti-matter containment and was destroyed as    Kim returned to his original reality.
   Named after America's oldest and largest national park.
   "Non Sequitur" - VOY.

Type: Runabout
Length: 26m
Beam: 15m
Speed: 7.5
Armament: Six Type 10 phasers