If I was having a to answer the same question, this is how Iwould go about it.
I would install a clear plastic drain tube that was longenough that I could loop around and over the top of the transaxle wheninstalled in its standard orientation. Iwould then fill it and record the height of the oil relative to the lower gearcluster shaft in the gear box. I amassuming that the oil level sits below the centre line of this shaft. When in operation the gears pick up the aeratedoil as the splash through the bottom of the case. I would then drain the oil, flip the case andinstall a similar drain line in the inverted box. I would re fill the box until I had achieveda similar coverage of the new lower shaft. The only thing to watch out for may be if the ring gear now sits in alarge depression and would be likely to sit in a pool of oil, causing excesswindage, drag and potential for hydroscopic pitting.
Anyone care to comment on that methodology?
No idea if its right, however getting an answer from someonelike CMS does seem like it’s a better idea.
Ryan