1999 Ford Windstar Battery not charging

Electrical problem
1999 Ford Windstar 6 cyl Front Wheel Drive 180000 miles

I've got a '99 windstar that doesn't seem to be charging the battery properly. I have a Haynes manual that gives a brief description of things to check. I checked the battery output and it checked out at 13V. The alternator output with the engine running was 13V also. This should be 14V+. The book also mentioned to check the fusible links in the wiring harness. I can't find them. Do you know where they are?

Also, the book tells how to check the voltage outputs from the alternator on a 3.0L but I've got the 3.8L. The 3.0L has a removable voltage regulator but the 3.8L doesn't. Additionally, the 3.0 has an A, I, & B terminal only but the 3.8 has the B terminal as well as a 3 pronged plug. So which is the A & I on the 3.8?

One last thing to check before I spend $200 on an alternator. What is the best way to check the wiring harness chargind circuit for shorts or bad grounds on this charging circuit?