First expensive truck purchase.

[Owen17]

I’m looking at purchasing a newer truck to replace an old one I have on the farm. The truck I’m looking at is a 2009 Peterbilt 389, 46” sleeper, Cummins ISX 485 with just under 700k on it. No rebuild has been done on it. The truck spent most of its life in a rust free state and the interior and exterior are extremely clean. 10 speed. Truck also has a wet kit. I’ve test drove the truck and it feels great running down the road. It has zero leaks. He’s asking $79,000. I’ve never spent that much on a truck, my biggest concern is buying this truck and having major engine problems after putting some miles on it since it already has 700k on it. Is this something I should run away from or take the gamble and buy it?