Alternator ?'s

[BK911]

Hello!

The alternator on my 72E has stripped rotor threads. I replaced the entire assembly with an alternator from a 73T. Now the warning light somes on until about 3k rpm's. I took the assembly back out to test per the workshop manuals. I found the resistance between the slip rings to be around 4.2. The spec is within 4.5 - 6.5. I assume this is the low voltage problem?? Also, I have an alternator from a 70 and a 71. Would either of these work? I heard something about the regulator has to be matched to the alternator.

Thanks!
BK