Should be a total of three bolts per mount. One bolt holding the arm to the mount and two holding the mount to the frame.
I'll be doing mine as soon as the mounts arrive, and in looking at the job, it looks like first you'll need a 19mm to get the main bolt. That bolt also appears to hold down the heat shield. Once that bolt and shield are out, lift the engine and remove the two cap screws (6mm allen I believe). Now slip out the old and the new in. Replace the two cap screws, lower the engine and install the main bolt and heat shield. Do one side at a time.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.