I have a 1993 G20 with a 5.7 liter V8. It has plenty of power, great mileage on the highway, and can haul just about anything. I bought it with 53,000 miles and now has 65,000 miles on it. I have had to do nothing to it but general maintenance. I am very pleased with it and hope to have it for years to come. It drives and runs like it is brand new.
Bought used April 2004 with 94,500 miles. Van now (July 2006) 125,000 miles on it. It's a G20 Shorty (180in long) with a 4.3L engine. The front end is excellent, compared to Ford van. Gas mileage ranges from 17 (city) to 20 (highway) at 65mph. Engine has been very reliable. A/C is a constant problem. The A/C compressor has been replaced twice in the last two years, and is broken again now. The factory jack is very clumsy to use.
I just bought a 93 van. Its my first Van and first GM product. It has 198K and still runs good. Smokes a little on start up but that's expected for its age and mileage. A/C had some minor issues with leaks that I fixed. 4.3L surprisingly has enough power. Gas mileage has been fairly good also considering its age and size of the vehicle. Very fun to drive. We are planning several road trips now and will be using this van to site see the states.
I drove this vehicle from New England down to Florida and it was pretty dependable and fuel efficient (20+mpg/hwy) considering the size. However, it was under powered when climbing up hills. Overall, it's an excellent economical work horse when it's fully loaded.