Galaxy has 30% more internal volume than Nebula, pod included? All due respect, but that figure seems to me to be a bit off, at first glance. I know the engineering hull is shorter than that of Galaxy, but it doesn't seem THAT much shorter. And most of the part that seems to be missing on the Nebula but exists on the Galaxy appears to be the wide, flat parts that support the nacelles as well as the flaring part of the neck that, while sizable, doesn't seem to me to make up the 30%. Also, Nebula's pod, while not very tall, is still pretty damned big and the pod supporting strut (at least on the tac pod variants...have never gotten a close look at the sensor pod supports of the Phoenix-type variant), and those two structures (pod and support pylon) would, I think, go a long way in making up a volume shortage vis-a-vis Galaxy.
The Starship Spotter book of 2001 mentions that Nebula has a cargo pod and a probe pod in addition to a tactical pod and sensor pod...have we seen any of those variants? I am also thinking that such pods can't be too much taller than the tactical and sensor versions, or else they'd interfere with the ship's warp bubble.
(Starship Spotter gives 3,309,000 tons displacement for Nebula and 4,500,000 tons for Galaxy, making Nebula 73.53% the volume of Galaxy...nonetheless, given those stats, looking at side/top/bottom/front/back views of both types, I still don't see THAT significant of a volume difference. What am I doing wrong?)