I once thought I needed a new transmission because there was an awful clanking coming from it at certain speeds. I took it to Weaver Transmission and told them I thought the transmission needed to be rebuilt. The next day they called to say it was just a chassis brace under the car missing a bolt, causing it to rattle at certain speeds.

They charged me like $50 to tighten it when I was fully prepared to pay them thousands to rebuild the transmission. So I'd trust them for transmission work even though I've never actually needed them to do any for me.