1999 Express Steering Gear box adjustment

Can I tighten the steering gear box a little??Reasons is I always need to be steering 100% of the time!! My control arm is tight,i had the front aligned,got new tires.BUT this is my 1st conversion van its a MARK 3,with the high roof!!!,Is this a driving characteristic???I'm I being to picky? Because my other vehicle is a 2008 z71 with rack pinion steering...Did i get to use to a rack and pinion steering and forgot what is was like to drive a older vehicle??..so is it the driver or van?? If its the van can anybody tell me how to adjust the gear box !!!

These vans have a much larger frontal and side areas. They have to deal with greater wind loads especially cross winds. How many miles on this van?
. I would check the entire steering system first and replace any worn parts before messing with the steering box,(worm gear), adjustment. The OEM proceedure for box adjustment is very precise and critical. The gears usually wear most in the straight ahead section. Even slightly over adjusting the worm gear will seem OK at first in the straight ahead position but can make the steering bind up in turns when under a load. That can be very dangerous and accelerate wear to the box at the very least.
I'd check the steering column shaft coupler for wear first as this is where most play occurs and replace that as well as any other joint and links as needed. If the wear is in the box and if it's high mileage I'd replace the steering box with a reman unit.