Back when my used 2001 Bobcat 773 was "new", with less than 200 hr, the alternator quit charging. This was way back in 2004 or before. Bobcat dealer wanted $ 200 + for the Denso alternator. At the time, similar Denso alternators were available from auto parts suppliers for $ 125. Went to Quality Rebuilders in west Knoxberg; the diagnosis was a faulty diode trio. Though they stocked parts for Denso alternators, this one had an "OEM" intergral regulator assembly-- more or less a mirror image of the "standard" Denso replacement alternators and parts, probably to keep people from repairing them, forcing folks to buy the OEM from the Bcat dealers.
The repair guy took his pocket knife and split the integral sealed regulator. There was no room inside the part to add anything, so he simply soldered on a generic diode trio, leaving it hanging outside of the now un-sealed regulator. Tested it--it's fine! Epoxied the regulator back together, and the alternator was ready for service. I don't remember what it cost me then, seems like it was $ 16 labor and $ 4 for the diiode trio.