2010 Chevrolet Avalanche Were the previous repairs serious?

Past history is not a good judge of future problems. I've had cars with pretty serious issues that were handled under warranty, then they were problem-free for another 150,000 miles.

The pinion gear bearing suggests there was a noise or howl, and the gear lube change at 40,000 miles suggests that was the first attempt at solving it. Leaking hoses are common today on all cars because manufacturers are using various kinds of snap together fittings to save time on the assembly line. They never seal as well as old-fashioned hoses and clamps.

Shock absorbers rarely fail at 53,000 miles. Some people think new ones are needed because they see so much advertising for them. The previous owner may simply have not liked the ride quality, or one might have started leaking a little. How much leakage is too much is open to interpretation. If the mechanic is paid a commission to "find" defective parts, it's more likely those shock absorbers "needed" to be replaced. Fortunately, almost all mechanics at dealerships and small independent repair shops are not paid a commission. The chain stores that cherry-pick the high-profit services are usually the ones that pay mechanics on commission.

The transmission filler tube is hardly anything to be concerned about. Very few people ever have the opportunity to see the list of previous repairs to a vehicle they're considering buying. The information might be nice to know, but don't let it keep you awake at night.