My K25 has been a daily driver, on and off since about 2002 when my oldest son starting driving it to school, followed by his younger brother taking it over 3 years later. I have a few suggestions about how to keep it reliable.
- Fix things as they go along, and fix them correctly, using the right parts. If the book says you need to replace additional parts as part of a repair (for example, when you replace brake pads there are other parts to replace), then do the job like you were a repair shop getting paid for it. Use the right lubricants, and check everything with your torque wrench. You don't want the customer (you) to come back with problems.
- Sticking with a configuration very close to the factory setup will be more reliable and require less tweaking. For example, running stock 31" tires and no lift is not that exciting, but it will require less fixing over the years. When you run a lift and big tires you need dropped steering arms and new springs, and your tires/wheels will need more offset to fit in the fenderwells. I am not saying this is bad, but if you leave it stock it will simplify your maintenance. When you run wheels with more offset you should be servicing the wheel bearings regularly and looking for wear. If you run stock tires and wheels you can run it for many years without even worrying about it. Stock tires are also cheaper, and available everywhere if you need a replacement (Walmart, etc.).
- In some cases, converting to a more modern configuration (LS engine, EFI, etc.) may make the truck more reliable, but make sure you are really getting a complete, reliable solution. If you buy a partial solution and then have to figure out the final wiring, fuel supply, etc. on your own, you just became your own personal automotive engineer. This is not fun if you started your project Saturday morning have to use the truck again to go to work on Monday.
- Make small upgrades that will help the truck be more reliable and work better. For example, gas with ethanol eats up the old stock rubber fuel lines, so swapping in new EFI rated hoses will reduce the possibility of a leak. When you replace bad rubber bushings, use the poly bushings that should last longer. Or when you buy brake pads, buy the performance version instead of the stock replacement.
Bruce