When Leonard Nimoy was directing STAR TREK III, he told ILM that the Excelsior should look much more advanced than the Enterprise. Nilo Rodis produced several different concepts, most of which had a very long body and four nacelles. Bill George then made study models of each of them, throwing in an additional design of his own, which was eventually chosen.
The original study models were later used as part of the Starfleet graveyard in 'The Best of Both Worlds, Part II'. The model is approx 5.25" (13.5 cm) long.
