how to drain a 904

Seals tend to get brittle when they are stored dry.

I always store them with fresh fluid and a filter in them. Put a yoke in the tail and wire it in place by going around the tranny mount to keep it in place. I put a piece of metal with tangs welded on it to keep the torque convertor in place and it is bolted across the case. I make sure and run a bolt through the dipstick mounting tab and wire the dipstick to that tab so it can't be removed. I store them just like they would be sitting in the car. I have stored them that way for years and so far I have never had one that had gone to crap when I used it.

To drain it, I usually attach it to an engine stand and do it just like it was being done in the car.