Ron,
I will be converting both 56s over to alternator this winter and the 3-wire is the way I am going to go.
Besides the info here, the following two links have some good info:
http://www.madelectrical.com/electricaltech/onewire-threewire.shtml
http://www.madelectrical.com/electricaltech/remotevoltagesensing.shtml
There is also a good article in this month's Mustang Monthly on TS electrical systems:
http://www.mustangmonthly.com/howto/mump_1112_how_to_troubleshoot_your_charging_system/index.html
HTH
Jim
Norfolk, VA

"MABLE"
1956 Thunderbird Green / Brown Interior (ZE-XG)

"MEAN GREEN"
1956 Mainline (FG-BE)