All about the same. The vb/gov set ups are what makes them different. The earlier units have a bushing in places that would get upgraded by a decent person doing the overhaul. The sun shell and stator support get replaced during an overhaul.
Really the most important stuff, at least to me, is getting the internal pressures up to the needed level, setting the clearances correctly, and getting the tv cable setup so the pressure jumps when the throttle is applied.