SD20 Saildrive question

[Quickstep192 93]

I'm preparing to change the gear lube in my SD20 saildrive and the owners manual leaves me wondering if there are two places to change it or just one. 
 

I see references to the upper gear case and the lower gear case. They reference different procedures for in the water or out of the water with references to the upper gear case and the lower gear case, but the lube appears to be ending up in the same place. 
 

So, my big question is:
 

If I drain the gear lube from the lower unit and then replace it from the dipstick port, am I done, or are there two separate chambers - one for upper and one for lower? 
 

As always, any guidance is appreciated. 

[Plumbean 33]

One chamber.  Drain from the bottom, fill from the top.

[Plumbean 33]

The manual also covers the SD50.  The references to changing lube while in the water only apply to the SD50.  For the SD20 just look at Section 6.1.1.  Removing the fill cap in the upper case assembly will help the oil drain once the lower plug is removed, but it is all one cavity.

[Quickstep192 93]

1 hour ago, Plumbean said:

The manual also covers the SD50.  The references to changing lube while in the water only apply to the SD50.  For the SD20 just look at Section 6.1.1.  Removing the fill cap in the upper case assembly will help the oil drain once the lower plug is removed, but it is all one cavity.

Aha! I was trying to read thoroughly and missed the part where they switched models. Thanks for the guidance. 

[Max Rockatansky 921]

Volvo is 20Nm

but here is a manual for your SD20:

https://www.yanmar.com/media/global/com/product/marinepleasure/sailBoatPropulsion/operationmanualgears/SD_OM_27MAR09.pdf