Pershing-class cargo drones. It was on active duty in Starfleet during at least the late 23rd. (Jackill's Starfleet Reference Manual: Ships of the Fleet, vol. 3)USS Pershing (NCC-G1400) was the lead ship and prototype of the
It was apparently derived from the Sherman-class cargo drone design and used linear warp technology.
Pershing was commissioned in the 2270s. All other vessels of this class had the nomenclature Pershing01, Pershing02 etc., up to Pershing99.