First arranger keyboard...a 73 Yamaha spinet organ...don't know the model number. Had auto bass. usewd it with two 147 RV Leslies.
That was the only way we could figure out how to get both channels working. Later got a second one (about 77) and switched to a twochannel leslie. It was ransistors, and I didn't like the sound as well as the tube models.

Russ