One has to wonder whether the shaft-driven (SDLF) system ended up saving any weight or money versus the separate lift engine (LPLC).
SDLF eliminates a (small) turbine gas generator but adds a shaft, gear and clutch. It also drives weight into the main engine (bigger LPT and shaft) where LPLC does not, and it tends to push you towards a shorter (hence fatter) body because you want to constrain shaft weight, volume and number of bearings. I should think that digital engine controls would still allow you to use differential throttle for pitch control in hover.
The Macs proposal was LPLC, of course, but there was substantial prejudice against that solution and there were other aspects of that offering that weighed against the team. (They had come together rather late in the game.)
It's all spilled milk of course - about 12 billion gallons or about 90 loads on this:
