Update on what we found

It appears that the replacement voltage regulator that we were supplied was not the correct unit. I received quotes from multiple forklift part distributors and they all said the replacement voltage regulator was part # CL336290. I purchased 2 of these and they each burned out after running for 10-15 seconds. I went to a generator rebuild company who was familiar with these alternators with external voltage regulators. The alternator tested good so they crossed the CL336290 to a Delco D635. They purchased two for testing and also burned them both up. They bought a third and wired it differently than our forklift. They wired it to a typical GM external voltage regulator and it worked. We made a wiring change in our forklift and it worked. Now I know the wiring in our forklift didn't change, so I continued to research why we had to make that change and that's when I determined that it must be the voltage regulator.

After cleaning off the surface rust of the original voltage regulator I found that it was a GM 1119507/Delco D632 but the replacements being sold for this forklift are equivalent to GM 1119515/Delco D635. I found many listings that show the CL336290 as being equivalent to many different part numbers including D632 & D635.

Since we spent so much time resolving this charging issue, we have decided to not try a D632 back to the original wiring, but I figured I would post this update for anyone in the future.