gearbox oil change on 1994 BMW 325i

hi there ,,, i want to get my gearbox oil change ....where is the gearbox located and what kind of oil should i use for best lubrication. and how to open the dash board where the stereo is located because the blower is makin some screachin noise which think is because of the less lubrication or dust sitting on it.
kindly help thanks

Asked by for the 1994 BMW 325i
The gearbox is located behind the engine and can be a tough job to change the gearbox gear oil if you have not done this before, We recommend having a Repair shop or Oil changer do this because if not done properly you can damage your transmission. Go to the Repairpal estimator and put in your cars info and click on Manual Transmission Fluid Change and your zip cost is about $80 to $127