Originally Posted by gweaver
I've got the same boat as you, except an 88. I tow with a 2004 Chevy Silverado 4.8 extended cab. We've towed the boat about 150 miles, two adults, two kids, boat toys, camping gear, food and ice for a week with no issues. I'd guess easily 700-800 lbs of stuff in the truck, a full tank of gas in the boat. No idea what mileage was, I'd guess 14-15? No major problems pulling the hills, either. I occasionally wish I'd gotten the 5.3, but truth be told, the 4.8 moves me just fine. Picked it up used for $7k.
Same boat... 89 Prostar 190. I tow with 2004 Silverado Z71 w/5.3. That motor is more than enough for a boat of this weight. It handles the boat very well and gets pretty decent milage. Not towing about 19-20 highway, 14-15 city. Towing the boat 15 MPG highway at 65. About 12-13 if I am in a hurry doing about 73-75. My average wknd trip is 135 miles and it is a nice ride. My buddy has a Suburban with the same powertrain and also loves it.