Why can I see gear teeth thru these transmission holes?

[Yogawrench]

My brother has a 1991 325i with the original autotragic transmission. It is the base transmission, not the "EH" version. Several months ago the transmission began shifting poorly or occasionally remaining in 2nd gear.

Tonite I put the car on jack-stands and inspected the transmission again. Looking at the left-hand/driver's side of the transmission, I noticed a "port" on the trans case that had 2 openings and 2 threaded holes for mounting screws. Using a mirror, I was able to see into the holes and observed gear teeth! On the back side of this "port" were the big initials "B" and "D". Here are two pics:





Additionally, in this pic you can see the "port" on the left, and on the right side of the pic you see a mounting bracket of some type. This bracket is on the inside left wheel well.



Does anyone know what this "port" is for? If there is a part missing, what is it? If this is designed for some add-on for the "EH" model, shouldn't there at least be a cover I'm missing? I have no real transmission repair knowledge, so feel free to 'splain what you know.

Help is definitely appreciated!

[MR 325]

That transmission was originally from an Eta. The Eta cars use those holes for crank reference sensors. You can plug them if you like but really it's not a big deal either way.

That bracket you are seeing is where the clutch hard line from the master connects to the soft line from the slave on stick shift cars.