Where is the resevoir for gear oil??
 

Hello. Yesterday I was checking the levels and I noticed the place that has the short dipstick was bone dry. I was told (because I don't have the manual) that gear oil goes there. I have been placing it in there the past 2 years. Well I accidently broke off the little prongs that secure it the port and wanted to order a new one. This is when it became confusing. One mechanic said clutch fluid goes in there and the other said transmission fluid. I recall seeing it somewhere that it's gear oil and I have not had a problem. Thing is I need a person that knows what they are talking about to tell me what goes there and if I am putting it in the right place. I took a picture of it so please help if you can.