Used Volvo 760 buying advice!! Regarding HP and Warranty.

I agree with this more and more as time goes by. Since the inception of the Onebox you can just replace the whole works for a few grand and it's all new and trouble free, precisely my plan on my truck in a couple years. But, you've got to do your research on every aspect of the truck model and it's particular history. I would not buy an early year emissions truck with high idle hours EVER. For me this means older than say a 2019 or so.

APU generally means less idle time but that depends on the company and specifically the driver. Part of the country where the truck was run can affect idle hours depending on more hot or cold weather.

Also this, emissions parts rust and wear much quicker due to the heat cycles. My 21 which ran team/all 48 has more rust on the emissions parts than my 2015 had at twice the miles, but it ran mostly southern states, less miles, very careful of staying out of the snow, etc.