Join Date: Sep 2009
Location: Live Free or Die, USA
Re: New to me, old to the family trailer
Looks pretty cool! That axle is set up like a full-floating truck axle. The axleshafts themselves don't support any of the weight, it is carried by the bearings. And yes, they were meant to be lubricated by gear oil in the axle. Might not be a bad idea to check the level and either change it or top it off if it is low.
For a suggestion, see if you can fit the tail lights in the corner between the bed side and the horizontal supports, under the angled metal brace rods. Should be a little more protected there. You'll need to make some sort of a bracket to bolt them to, but the perforated angle iron you have plus some bolts might work for that.
Probably going to want some sort of fenders, too.
"Felix qui potuit rerum cognoscere causas"
[Happiness is understanding how things work]