Chinatown Machine Shops

[tajartale]

Was wondering if anyone knows what the guys are doing in these Chinatown shops who are hammering at what looks like a large ball and socket joint, are these part of tie-ends? I don't know much about cars, so was wondering how it works. Are they taking the joints apart? Putting them back together? Are these truck suspension parts? Some guys were taking apart a differential, but these other guys are hammering really hard at these things that look like part of the suspension. Are most of these shops catering to trucking or are all these parts going to be sold on in the general market? It always seems a little antiquated, walking past all these places, but they're plenty busy, even with floods.

Any info on what these small businesses are about?