Well, a search for the "D40V2" transistor does come up with some info:
D40V2 Datasheet. D40V2 Equivalent, PDF Data Sheets - Parameters and Characteristics. Electronic Component Catalog.
Interestingly though I don't find that part number listed in the service manual for the D-150A II (available on the Crown website). Instead they show a "D40P3" in various places. Then again the D40V2 shows up in the Crown part listing whereas the D40P3 does not.
Plugging some of the info given for the D40V2 into Mouser's parametric search yields a possible alternate as a MJE15032G which also happens to be a popular driver transistor in many amp designs. But then again there may be unintended consequences such as oscillation and differences in pinout.
I think I would just order the dang thing from Crown if they still have them, hoping to avoid spending hours of trouble & hair-pulling just to save a few bucks. We only have a finite number of hours (and hairs) after all...
Crown Part # for D40V2 is "C 4061-5"