Most of the 2wd first gens I've ever come across had the sway bar behind the beams connected to the radius arms like alwaysFlOoReD said. Both my first gens were 2wd regular cabs (84 LB, 86 SB), and neither of them had a factory sway bar. IIRC the 84 was a base model fleet truck, and the 86 was an XLT. Even the aftermarket sway bar that I bought for the 84 mounted behind the axle to the radius arms.
IIRC the front bar I used was a Hellwig from Summit Racing. They are listed at $208 now, but they were a bit cheaper then I think. Regardless it was worth every penny and I'd buy it again if I had too. It's a bolt in affair. The mount brackets attach to the inside of the radius arm where the shock mount bolts on, and the bar mount under the radius arm cross member. Should be the same deal for a stock bar IIRC.
I had the same question about the studs on the front of the beams. Only answer I could come up with is that they are jack stand "pads". The later model SLA suspensions have something similar on the front of the lower A-arm.
Beams on 89+ (year they changed) aren't longer to my knowledge, and if they are it isn't enough to matter. The 89+ beams can be installed on a 83-88, but you have to change the steering knuckles as well since they mount differently. If doing all that work to get a swaybar, you might as well get 95+ beams, knuckles, and calipers to do a slight brake upgrade while you are at it. FWIW I've got this going into my 86, but I'm using the sway bar that I had on the 84, because it's larger than any factory bar and the 84 doesn't need it any more.