just my 2 cents on this 645 debate,, i have been running a 5645 for steering in my revo for over a year,, same one.. sure i have a backup but have only needed to use it twice when i had moshed the gears in the original one,, aside from replacing the gears myself twice i have had no problems with this servo at all. I always recommend hitec when asked about servos.. look at the for sale forums.. you have the 'oxygen' and "junior" used servos for sale all the time and hardly ever see a used hitec for sale.. makes me ponder who is really having the problems... again just my 2 cents.