Service Honda shows a different part number for the 350 with a major. price difference:
53150-HB3-003 JOINT, BALL 47.75 34.93
Quite a bit more than the $6.11 I paid for the 400 ball joints.
Maybe someone knows if the 400 will fit the 350. Wonder why the huge difference in price. Actually I was surprised how cheap the 400 joints were. This was a first. I'm always shocked at how much a part is.