Volvo Penta MD2020 saildrives that fit?

[timroving]

Hi all and thanks for reading this.
I have bought a catamaran that comes with two Volvo Penta's MD2020 19HP diesels with 2 not installed saildrives. One is a SD50 and one is a SD20 and I have an old S drive. None of these seen be able to fit as only the SD50 has a similar bell housing and all the spines and input shafts are different.
Can anyone inform me what saildrive is built for the MD2020 and can any others be easily modified to fit??
Thanks for your time. Cheers Tim

[tkeithlu]

I can refer you to this PDF from Volvo, which shows the MD2020 with the 120SE saildrive.

https://www.plaisance-pratique.com/IMG/pdf/md2020.pdf

[DougR]

From the beginning of 2020 production the engine was fitted with the 120S saildrive with a reduction ratio of 2.5:1. Then in model year 2000, (if I recall correctly) the ZF built MS25S saildrive began production and the engine was equipped with that saildrive. The reduction ratio was 2.47:1. The MS25S drive was kind of a hybrid with the top box designed by ZF and the lower leg built off of VP drawings.
My recollection is that the even later model 130S saildrive could also be fitted to the engine, but it wasn’t a production option.

You can tell which drive was originally installed on your engines by looking at the splines of the flywheel damper plate. The 120S drive had a smaller shaft with finer spline teeth, and the MS25S had fewer splines and a larger diameter.

The photos show the two dampers....first photo is for the 120S and the second photo is for the MS25S drive.