Doug, I didn't open the drive up but here are the part numbers on the unit.
Thanks John. Very similar to mine but the numbers don’t tell you what gearing has been fitted. And when you open the cover, nothing is apparent until you get the gear wheel to rotate half way and then find the number stamped which was hidden by the driveshaft when in the parked position. Anyway, have now ordered a 120 from CBS with fingers crossed.