I have a 6.2 in my '90 K5, over 100,000 miles and no major problems. It's not real fast on the road, it feels similar in acceleration to a fuel injected 305 pickup. Off-road it's great, lot's of low end torque and it will never stall or hesitate at any severe angles, and has plenty of higher RPM power for about 90% of the mud holes and hill climbs that require a little wheelspin. As an example of mileage, I went trailriding a couple of weeks ago that involved a 200 mile round trip on pavement, and about a 7 hour long tough trail. The engine was never turned off the entire day and it only took 16 gallons to fill up when I got back home......that's 12.5 mpg, not even counting the extra 7 hours on the trail! BTW, the K5 has 35" tires, 4.10 gears, and 700r4.