300K service on my truck. What's your highest mileage service you've done?

So last week after flipping over to the big 300k miles, my A/C compressor bearing locks up and flings the serpentine belt off on my truck. Luckily I was able to make it the 5 minutes to my house. I kind of needed to get the truck rolling for the next day and had a compressor waiting to go on I had bought a couple months back, so I throw that on there, but the extra heat must have finished off the waterpump and it's leaking like a sieve. Feck.. oh well guess it's time to replace that, (it was on my to do list anyways). Now on the 6.5L you have to take off pretty much every accessory to get to the WP, now looks like a good time to replace all the accessories then.

So I'm riding the motorcycle while I take my time replacing the waterpump and hoses, A/C compressor, vacuum pump, power steering pump and lines, and the harmonic balancer on the front of the engine. Then it's time to move to the rear and replace the lift pump and sending unit. And to top off all the work, new brakes, inner and outer tierods, ball joints and pitman and idler arms.

So what's your biggest high mileage service you've done?

I did a tenth timing belt service on a 1984 Volvo 240. That was at 600k. The power steering pump was still fine. Probably did 5 water pumps on the thing, they'd fail pretty regularly every 120k. Then again, the water pump is a 10-minute job, and the only thing you need to remove is the fan blade :)

Friend of mine has a 2001 Tundra with 570,000 miles. Has only changed fluids, filters, battery and alternators.

Did 328K on my 1995 Mitsubishi Mirage. Clutch, exhaust, still original. Up until then it was just the usual shocks, timing belts, regular maintenance stuff. But motor though running strong was leaking a bit, and the rear axle bearing/hubs went. I decided then it was time.

Coming up on 425k on my 2007 express. Not even sure what to do besides keep changing the oil anymore and being happy every day i make it home. Sometimes i feel like i'm driving a ticking time bomb

I inherited my mom's 93 Subaru legacy before I went in to basic and that had about 325k before It was sold (i was in Korea and they did not need a 3rd car)

I got to 265K on the last Chevy Astro as it rusted away. You can't get to any staggering mileages before the tinworm wins up here.

I don't know, on my C1500 the ODO quit working at 279K about 4 years ago! But I did just put a fuel pump in it as preventative maintenance before the old one completely crapped out on me (was down to 9 psi, bottom end of spec).

One of my VWs had something like 380k on it before I got tired of the biodegraded wiring harness and bought a new car.

One of my customers had nearly 700k on a Chevy van when he figured it didn't owe him any more and he bought a new van. He was a Landmark contractor. Van had a 5.7 "spider" style engine, still on the OE fuel system, intake manifold gaskets, and transmission.

He lived out of his vans while contracting. A few years ago, he was in Texas during a historic heat wave. He went 2 WEEKS without shutting the engine off. Engine (6.0 LQ4) apparently got up to 250F.