hi doug -
i also have a d3v, but mine is a war contract model. they have larger condensors than the standard d3v - so they could enlarge aerial film. these contract editions tend to have a large serial # on the head &C. if you end up with one, they also have a condensor head ( 2 lenses ) and a movable condensor that goes just below the light source. it is a great enlarger except this specific one does not take normal negative carriers (they leak light since the condensor housing is larger than normal ).
harry taylor has parts and knowledge about all the omega enlargers. if you have specific questions, he is quick to reply from his website. he also makes rails & has a supply of cones if you find yourself needing parts or accessories.
i also have a e4 and have variable focusing bellows ( for both the d3v & e4 ). these bellows are normally used for making "jewel prints" but i use them so i don't have to change cones &C when i change lenses. harry isn't a fan, but it saved me a few bucks in the end