My 1988 B2200 puts out great heat, better than my two newer Frontiers.
Nikki - I think the first thing to drive the truck 15 minutes or more, and feel the two heater connections that protrude into the engine compartment at the firewall. They should be HOT.
If both are hot, then your engine thermostat is working, and you have enough coolant in the radiator/system. So next would be to investigate is whether the cables that operate the little flaps or doors are operational. These are on both sides of the center console, best to have a helper move the vent/heat/defrost lever, the temperature lever, the recirculation/outside lever through their movements, and take a look. Unfortunately, this means flashlight and getting under the dash and looking up and to the center on the truck, 2 on one side, 1 on the other. I had a cable slip off on mine once, had to rig up a way to secure the cable on the door/flap operating lever.
Third possibility - if air does not come out the vents (either dash at windshield, dash, or underdash - would be that there are clogs in the air flow system, like leaves, clogged AC evaporator.