Alternator and electrical basics with a multimeter

OK, You first need a basic history lesson on Chryslers charging system. In the beginning they created what is known as a closed field alternator and the appropriate closed field regulator. That (mechanical) regulator had simply a blue wire at top receiving 12 volts at ignition switch on, and a green wire that went to the alternators field or one contact brush on its armature. the other side of the field was chassis grounded like nearly everything else that operated on 12 volts. Some still refer to this practice as "raceway" grounding. No ground wire is required because the body is metal. Thus the vehicle itself serves as a ground wire. Those alternators were called round back by the peeople that dealt with them simply because they had a roundish backside.
Now lets fast forward to the square back alternator which was a different electrical design know as isolated field alternator. This alternator used a different solid state regulator. It had the same green wire going from regulator to on contact brush on back of the alternator but also had a blue wire (same circuit as blue wire on either regulator type mention before). This blue wire energized the field so the green wire only senses and feeds back to the regulator where it is grounded. This alternator was and still is referred to as square back. The novice would call it a dual field alternator simply due to the 2 wires on field contacts/brushes.
There are reasons why the round back alternators are no longer reproduced. One reason, their output was only 36 to 42 volts. That is very minimal power by todays standards.
Cut to the chase, I'll sit here many miles away and guess you do have a square back alternator, be it brand new or reman'd. The parts clerk was correct when stating this alternator would work in your application. He likely didn't explain what the difference is and how to go about making it work. I will....
Assuming you have the correct regulator for closed field type unit, You would simply attach the green wire to one of the contact/brush terminals and addon a jumper wire routed from the other brush terminal to chassis ground. Now the isolated field "square back" alternator operates as a closed field alternator. It can produce 60 amps or more but not to worry. A proper functioning voltage regulator will not allow more system current than called for by the system.