Been out of the hobby for years, and a buddy tempted me with a good time, and gave me a hand me down 6s, when he bought his 8s... So I ordered up batteries, charger, new body, all that jazz... Long story long, blew the front diff. Ordered some parts, kept playing with it, and now the rear is making horrible racket. Guessing that one diff is not beefy enough to support the power! (Whoops) Is there a difference between 6s and 8s gear sets? Are helical cut gears worth the money? Or do I just keep a few in stock and get good at replacing them? TIA