Re: transmission leak at driveshaft/output shaft on C6?
Hi and welcome for the forums. Its more than likely the rear seal (Extension Housing Seal) that's leaking. Its a common issue and a pretty easy fix. Unbolt the drive shaft from the differential (if its a two piece drive shaft also unbolt the carrier bearing from the frame), slide the drive shaft yoke from the tail shaft of the transmission. Pry out the seal and in with a new one. I believe there are two different seals so you might as well take the old one it to match up to the new one. Also, if you'll jack up the rear of the vehicle you will minimize fluid loss when you remove the yoke from the transmission.