My 2007 309 has the factory installed windlass. 'Believe the brand name is Maxwell. Seems to work well enough. The capstan mounts horizontally in the anchor locker. Does your anchor locker have a big bulge in it?....it would be starboard side, aft, in the locker. The Maxwell goes inside that bulge with the capstan sticking out of the side.
The rubber footswitch mounts on the top of the bulge, inside the locker.
The windlass has a considerable current draw and it's recommended that the engine be above idle when you operate it. There's a separate, big switch mounted above the main fuse panel on my boat. I would assume they used some fairly heavy gauge wire to power the windlass.
All that said, I can't say that the windlass is in my top ten of best accessories on my 309. It's still recommended that you put your vessel in gear and power up to the anchor, not just use the windlass to take you forward, so the only "heavy lifting" the windlass does is bring the anchor straight up from the bottom. My Rocna anchor is 22 pounds. At age 57, and reasonable fit but not superman, I often don't bother with the windlass.