Found some nice deals while browsing craigslist this morning, saw 21" silver turbines off a 2012 MS for $800 (minor curb rash), and 6 months old silver turbines without curb rash for 1500. 1. Is that a good deal? 2. Will it fit my MS100D I will be getting soon (I got the slipstream wheels instead of upgrading through Tesla)? Are all turbines the same size? 3. Will the sc install it for me?