Idler arm rebuild kit, complete steering linkages (drag mount too). You'll need the MB spring compressor (rent from IMPCO or
rusty@mbz.org) to pull the springs out. You'll need a press tool of some sort for the ball joints, I made the AutoZone free rental tool work (it ain't pretty and requires removal of the grease boot). You need to pull the hubs, so either replace the bearings, or at least clean & re-pack them with fresh MB neon-green grease (measure out the specificed amount with a postal scale or something). And you'll need a dial gauge to set the wheel bearing play. Here's some photos of my W123 rebuild, where I also replaced EVERTHING up front except the coil spring itself:
http://www.meimann.com/images/mercedes/W123_suspension/
Kevin, the guide rod bushings usually don't wear badly, and are an OE dealer item only - about $20 per side, probably more if you don't have a discount source. Check your before replacing, mine were OK, where EVERY other item on the car was SHOT. My guide rod mounts were destroyed, as were all the rubber bushings and joints. It was amazing the front end hadn't fallen off the car yet!
HTH,