Yup...that's it.  Both sides of the axle are directly tied together.  It doesn't slip what so ever.  It's cheap, cost of a few welding rods, but VERY permanant.  On-road handling suffers, just as you saw with you buddies, and it's hard on tires.  Off-road, it is what it is, full power to both wheels.  If I myself were to "lock" a D-35 (what you have), it would be by welding it.  The D-35 is a weak axle, and not worth throwing the money of an actual locker at.  You would be better money spent up-grading your rear axle to a Ford 8.8 or D-44.  You can get the axles at a junk yard or Craig's list for cheap (couple bills maybe), then spend the money on the right lockers.  You probably have 4:11 gears now, so that is what you need to look for.  Swapping out axles is not that big of a deal.  If your wanting to go cheap, weld the D-35, and when it eventually breaks, and it will, up-grade to a bigger, stronger axle.