Dan is correct :thumleft:, I would say 4 to 5 quarts if the converter and pump is ready to fire up, I just did did a change on my old 1985 904.
I would recommend the rear end to be off the ground safely and put 3 in and fire it up and the the fluid run threw the pump and shut it down, Look at the dip stick then, It's easy to put it in and when its to full it must come out
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