Haldex fluid question (Volvo content)

I finally had a chance to get under my recently-acquired Volvo V50 to deal with the last fluid I hadn't changed, the unicorn tears oil in the Haldex unit. Ideally, I would have drained the whole unit and changed the filter, but time was limited, and since doing it properly requires dropping the end of the driveshaft and pulling the flange out of the unit in order to pull the pump to clean the screen and get all the fluid out, so I settled for sucking out what I could through the fill plug and replacing it (I'll do the full change in the spring). Once I got the plug out, however, I found the fluid level to be lower than I could reach with my finger, so I went straight to filling it. It took ~250ml of fluid.

The question is regarding the final level. I cannot find any definitive information on whether it should be full to the hole (which seems the obvious answer), or whether you have to drive the car for a short time, then drain either 40ml or 100ml out through the fill hole. This is a Haldex 3 unit in a 2006 V50 T5 AWD. Having seen a good video that shows one of these completely disassembled, I can't imagine how leaving it full would be a problem, unless the oil has a lot of thermal expansion (I don't know if there's a vent). Does anybody know what the right procedure is for setting the level?

I've always filled to the hole.  

Was that in a Volvo? If so, what year and model? If not, in what? Just trying to get a sense of which generation of Haldex you were dealing with. Am I correct to assume you did not have any problems after said filling?

I own a shop that deals with a few hundred Volvos, and have never seen any generation of Haldex that wasn't full to the plug.  I'm not really sure how yours was low, unless somebody changed the pump and didn't refill properly.

In reply to Streetwiseguy :

Well that's pretty definitive - thanks.

As to why mine was low, I have no idea. The unit was externally dry and showed no signs of leakage or being cleaned; I found no record of any work being done on the Haldex (though the records on this car are incomplete). None of the other fluids have been low, and the car seems to have been maintained reasonably, so I really don't know what the deal is. My plan is to run it through the winter, then take the filter and pump out, clean everything, and refill. The AWD seems to be working, so I'm just going to send it and hope for the best.

Thanks for the feedback.