Yeah, in my case the gears were shot and I ended up replacing the lower unit with a used drive I found on craigslist. Still don't know what caused the failure but have to assume I hit something on the lake that day.
Hopefully your issue is different, and easier/cheaper to repair!
I have a 2008 Regal Commodore 2665 powered by a VP 5.7GXi-H w/ DPS-A sterndrive. I was out on the lake over the weekend running about 30mph when my boat abruptly lost power. The engine was still running, but there was no movement from the propeller. Tried shifting into gear forward and reverse...