1989 5 sp trans fluid change question

I can't seem to find the fill plug on a 5 speed trans. the vehicle is a 1989 jetta diesel. I found the drain plug and thought the fill plug should be half way down the side of the trans as on an anerican standard transmission. any help or direction would be greatly appreciated.

You actually are supposed to fill through the speedo cable hole. There is a plug on the driver's side of the transaxle, facing the front left tire, which looks like a fill hole, but actually there was an oddity with these units. You actually remove the upper plug & fill untill fluid runs out it, then put the plug in and add another 1/2 quart.

Thank you Boschmann

My manual 5 peed will only shift into 3 and 4th gear. No reverse, 1st, 2nd or 5th.
Any ideas?