You need to...........
Download a free factory manual, here
http://www.forabodiesonly.com/mopar/showthread.php?p=1970088617
and more manuals and other stuff here
http://www.mymopar.com/index.php?pid=31
Read the manual, section 8 about alternators. We can step you through some simplified tests
PLEASE READ this article. You don't have to DO this mod, just read the article
http://www.madelectrical.com/electrical-tech.shtml
It does a couple of things for you. First, it points out the pitfalls and the whys of the wiring in these old girls Second, there's a simplified diagram on that page which shows a good overview of the major electrical distribution in these cars
THINGS to watch for. As I said, we can step you through
Can you post the part no and better yet a photo of the newest alternator you have? The rebuilders of late "play games." Here's the thing. THERE ARE three or four major "big splits" in the types of alternators that would fit and be made to work--------without mechanical alterations------on your car
They are............
1......First year up through 69 alternator which has a single field connection, and one grounded brush
2.....1970---73? so called "round back" with isolated field, that is, TWO insulated brushes.
3.....1969 /earlier CONVERTED to insulated brush by the cheap rebuilders
4......73? and later so called "square back" with isolated brushes.
Your car has the "early" style regulator that is one insulated brush holder. You can use the LATER alternators (1970/ later) by grounding either brush and hooking up to yours as per normal
================================
The problems..........................
you might have inadvertently gotten an isolated field unit, either original or rebuilder converted, meaning one brush still needs to be grounded to work
you might have a defective rebuilt alternator, not uncommon
you might have yet another defective regulator, not uncommon with today's "Chineseo" junk
VERY FIRST THING TO TRY
First, buy yourself some tools if you do not have them. Buy a bag or two of Radio Shack test clip leads. Buy a digital multimeter. Everybody sells these nowadays, parts stores, Sears, Lowes, etc
But a 12V test lamp and a spark tester gap from the parts store.
Unhook the green field wire at the alternator. Hook a clip lead from the big alternator stud to the field terminal on the alternator. BE CAREFUL. That big stud is HOT and IS NOT FUSED.
In subdued light, you should see a small spark. Start the engine, bring up RPM. The ammeter should show charge, more as RPM comes up.
Post back with this result