Nope. New ones. I really don't care if it voids the warranty, I'm not going to run a TTpro 40 in Q500 racing without a rear bearing with a plastic retainer. In 2009, my best engine puked a rear bearing and carved up a piston/sleeve/head combo. Not going to do that again. We had three club members that summer lose good piston/sleeve combos due to stock rear bearings shedding pieces of the retainer cage. None of them were rusty or corroded, they just weren't up to what we were asking of them. 16,500 to 17,000 on the ground with a 9/6, who knows what they unload to in the air.

Bearings are pretty cheap compared to the cost of all those parts. I've been buying stainless from rc-bearings.com and had good luck with them.

I did buy one used TTpro .40 engine once. It's about 500 RPM down from my other three, pretty worn. It's good for practice, but when race day comes, it's staying home.