Tommy James flew this alternator with the 13B I bought from him in about 2006, and I’d like to run it in my install but was wondering how to hook it up.  I assume the “L” would run to the failure lite, and the “S” is the “Field” circuit maybe?  

Doug

'S' typically means 'Sense'; it's to measure voltage at the load. Long lines or resistance in the lines can result in undercharging the battery if output voltage is sensed directly at the B terminal.

'L' is typically for the idiot light, as  you thought.

'B' is the output (fat) terminal.

There should be another terminal labeled 'IG' or 'I' or something similar. It's used to turn on the regulator at initial engine start. Some newer alternators will shut down if power is removed from the IG terminal, but most older ones cannot be shut down once they come alive. (Even if removing power from the IG shuts the alt down, it can't be relied on to shut it down if there's an internal failure in the regulator inside the alt. Most internal regulators are in the ground path of the field, so if the output transistor in the regulator fails shorted, the regulator cannot control the field and removing power from IG will have no effect.

Here's a 'typical' diagram for an internally regulated alternator. Hope it helps. :-)