I fly both 737-300 and -7/800. The 737 AFS compromises two FCC computers (so 2 channels) controlled by one MCP panel (on wich there are two AP switches, A and B). This makes the system fail passive(one AP failure means no autoland). The 737 is capable of CAT IIIA autolands without coupled rollout, i.e. the pilot disconnects the AP shortly after touchdown and performs a manual rollout. For CAT IIIB you need a fail operational system(3 AP's). One other option is to have a head up display installed, in this case you can fly manual to CAT IIIA minima.