I am looking at used full size chevy trucks online. Is one from the 90s with 100 – 120k miles going to be more reliable than a 2000-2003 with like 180-250k miles?
You should be looking at the condition of the car a lot more than miles… I’ve seen and had junk cars with low milage on them… I’ve seen and had high mileage cars that were very good cars.
Reliability is determined by condition and how well the former owners maintained the car. Miles alone isn’t enough information to base your decision on.
A well maintained truck with 150k miles is going to be a better vehicle than a truck that has been abused and ignored but only has 80K miles. The age of the truck isn’t all that important. If the truck has been well maintained the year it was built becomes less and less important.
You should be looking for a well maintained truck in your price range regardless of age.
That’s a lot of miles on a truck. Trucks are basically beat on every day. I suggest you scale it back to a more affordable mid size truck modern and low mileage. None of the options you’ve presented for yourself are going to make you happy 6 months to a year out.