I'm looking at a 2015 GMC Yukon Denali from a private seller in Sharjah and the car has a bit of a shudder when accelerating from a stop, which makes me nervous about the torque converter. I found a service at https://prepurchasecarinspection.ae/brands/gmc/ but I have no idea if they actually know how to test the 6L80 transmission for the common issues or if they just do a basic visual check. Has anyone here used them for a GMC truck or SUV and can tell me if they put the car on a proper lift and scan for transmission slip counts? I don't want to waste my weekend driving out there only to get a weak report. Appreciate any real feedback.

Shudder on acceleration from a stop is such a classic torque converter symptom on the 6L80, worth specifically asking whoever inspects it if they can pull actual transmission slip counts through diagnostics rather than just judging it by feel on a test drive.

A proper lift really matters here, without it you're limited to what you can see and feel from underneath with just a jack, which makes it harder to properly inspect mounts and check for leaks around the transmission. Worth confirming upfront whether they'll actually have one available.

Can't personally vouch for that specific service but the shudder you're describing lines up almost exactly with the known 6L80 torque converter issue on these Yukons. Make sure whoever you go with actually road tests it enough to feel that themselves rather than just relying on your description.

Slip count data specifically requires proper scan tool access to the transmission module, not every inspector pulls that level of detail. I'd call ahead and ask directly if that's something they check as standard before committing your weekend to the drive out there.

Had a similar shudder issue on my Tahoe from the same platform, ended up being confirmed as early torque converter wear once someone with the right diagnostic tool actually looked into it properly. Worth confirming they check for that specific issue before booking anything.