If the lenses are good, I'm bettin the bulbs are old. They are halogen lights and over time they eventually burn off enough of the gas that they get "dim". I polished my lenses and replaced the bulbs with Xenon bulbs and WOW, my lights are awesome!
As far as runnin hi and low at the same time, my only concern would be melting or burning the lenses, there's not a lot of room in there and the heat would concern me.

 

Bulbs dim over time. Replace the bulbs (Not just the bad one...Both of them!).

 

this is why i like the old sealed beam lights. they always look fairly brights for the most part and it is pretty much cheaper to replace them then polish them. i plan on trying to have the high beam and low beam on at the same time on my truck. the worst that could happen on my truck is i blow a bulb.

 

yeah i got my lenses polished today no luck guess the new bulbs is my next go around

 

i just went out and tried having the high and low beam lights hooked up at the same time. on my truck it was definitely twice as bright but i don't know if there is any bad long term effects. definitely do not know how well it would work on a 2nd gen but i don't think it shouldn't make it any hotter and melt the lens. the only way to find out would be to try it. maybe get some cheap lenses from the junk yard to experiment on.

 

yeah our lights run on a open circuit, there really dim, checked the fuse under the hood and it was blown didnt even look blown ,used a volt meter on it and it was no worky

 

Well even with stock bulbs, if the hi beam is on (60 watts) and you also have the low beam on (55 watt), it only makes sense that they appear "twice as bright". Having said that, it only makes sense (to me) that it will also be twice as hot !

 

Check the inside coating on the bezel. Mine were dim and one side looked black. Took the plastic cover off and the chrome was gone inside. Painted it with some chrome paint. Much better but still not as bright as I would like them.

 

Now, I don't know about the wattage on the 81-93 Rams, but the proper headlight wattage for our Rams is 45/65 watts.
Granted, the 99-02 Sports ran 55/65 watts...

 

from what i have found on the internet the sealed beam lights used on the 81-93 are suppose to be 35W/65W but i think that 35 watt would be running lights if it had them because the high and low beam seem to be the same brightness but pointed at different places. it would not surprise me if the the 2nd gen lights are similar and that 45watt is the running lights if it has them.