Steve, First of all you are limiting yourself WAY too much for no reason. (manageable parts list, battery interchangeability) These are non issues in old truck life.
Since you have already made the jump from generator:
1. As your charging systems go bad, switch to internally regulated alternators and get rid of all the extra parts/wiring. Using an externally regulated alternator is half way to heaven.
2. Batteries are interchangeable for testing one vehicle or another. With jumper cables or longer cables. They don't need to be interchangeable if they are bad. You buy a new one.
3. If it takes revs now and didn't before. maybe your idle has dropped or you have some loose or corroded connections. Residual magnetism, which begins the charging at start up, is not used so much in 10si alternators. They use battery power to excite the alternator.
I don't know what a DN style alternator uses. Make sure you have a good, load tested, 12.6V charged battery, first.
Delco 10si
Alternator. si= system integrated= internally regulated. 3 wire hook up. Better to have one component for charging, not alternator and regulator with many connections/wires.
If there is a charging problem and connections are clean and tight, battery is good, then one component @ $55 free ship, 20 minutes and you are fixed. No testing required.
You can test, disassemble, clean and rebuild them with diodes and regulator for $15, but the delta is only $40/no DIY risk.
Let us know if you agree with suggestions or have questions. Glad to help.
