The exploded diagram you have shows a gasket between the case and the steel cover on the front.
Volvo said there is no gasket on my 2002 trans.
Is that correct??? And why is the dipstick located directly below two hot hoses????
That makes hard to see and not possible to check level when the engine is warm.
When I brought it to the local mechanic he wanted approx $600 to repair.
If that was the only issue with the car it might make sense.
Since I don't have any resources I thought I might try it myself.
Two of the Torx fasteners cannot be accessed without removing the trans.