Welcome from KY! I think there are many variables to consider here. How much are you purchasing the Suburban for? How would you feel if a $6-$8k repair bill was to unexpectedly fall into your lap? Would you still feel like it was a good buy? Test drives sometimes go so smoothly because as a buyer, we are already excited at the "new to us" thought of the vehicle and may not be quite as alert to issues as we'd like to be.
I ask because of my journey, which I'll map out as short and sweet as I can...
May 2023 - Purchased 2015 Suburban w/184k miles for $17,500
June 2023 - Various repairs done at home (liftgate actuators, drivers door lock switch, shark-fin antenna, thermostat, water pump) totaling around $400.
Late June 2023 - Significant lifter tick present after oil change (suspecting the previous owner used all the tricks to minimize this sound before trading to the dealer I purchased from)
Early July 2023 - Transmission starts showing signs of significant issues (shift delay, extensive TC shuttering, etc)
July 2023 - Engine completely dies. Cylinder 4 lifter totally collapses
My Suburban is now awaiting an engine and transmission, looking to spend in the neighborhood of $10k when all is said and done.
I say all that to say this....
As much as I hate to spend this money, I still feel like I got a relatively good deal considering that I purchased it at (what I felt like) was such a low price compared to what else was and is on the market.
Common failures you may see....
1. Engine failure due to AFM/DOD systems
2. Trans failure due to a poorly designed trans that runs hotter than it should at all times
3. Compass/navigation failure due to shark fin antenna taking in water and shorting out
4. Rear liftgate shocks failing due to the left side shock (which houses the actuator) failing
If you made it this far...I hope this helps!