I bought my front shocks from NAPA. I wen to their web page and they actually had a listing for the available shocks to fit my 54 3100.
But the OP has a 3/4 ton, which don't appear on many listings (old truck vendors, mainly).
To me, the front looks like it has the same type of weld as the rear. I still think that the rear was probably the original but its hard to tell due to the bracket being bent and missing a chunk.
I couldn't tell if the front mount was welded from the pic. But you may be right about the rear mount being original, as it doesn't look as redneck as the one the shock is connected to. It's a formed bracket of some sort, but I would have expected it to be riveted if original.
