Help with the AC system in my 1987 Dodge Dakota.

You wont be able to recharge it because it uses r12 frion, which was banned in the late 90s, (my ‘90 Chevy still has the factory air) you would have to have it converted to an R134A system, trust me let a qualified shop do it, it requires special equipment. Generally people think their a/c just needs a recharge, but there is usually a reason the refrigerant leaked out in the first place.

Buy a new one