If I remember correctly, it takes a 30mm thinwall socket. I have one
somewhere in the trunk of my car. Bought it trying to disassemble a
Getrag 5 speed. Same nut that's on the ZF automatic though. BTW - The
Getrag NEVER did come apart. it's waiting for the sledge hammer wrench
to be invoked. I WILL get it open...

It's the vibration damper which is between the driveshaft and the
transmission output shaft.  I had a difficult time with it because there
was about a 34mm nut at the bottom of that that I couldn't remove
because there was very little clearance between the nut and the sides of
the damper (I suppose you could call it a donut) in which it was
situated.  I had no sockets which were both deep enough and thin enough,
so I wound up hitting the corner of the nut with a drift and a hammer.
Not a good way to treat a nut, but I couldn't see any other way to
remove it.

Ed

By damper, I assume you mean the rubber propshaft dounut?  I am not sure why
this caused you a problem.

As for the upper bolts/upper starter motor bolt, a long 3/8" extension is
the key, so you are undoing them from the back of the gearbox.

I'm not so sure about that.  Have you done it?  When I removed my
transmission on my '86 325, I had a terrible time trying to get the
damper off the back and the top few bolts off the transmission.  I
finally used an engine hoist to tip the engine up and then used a 36"
extension to get to those last two bolts.  I wouldn't have described the
job as easy, exactly, but maybe that's because I don't know what I'm
doing.  If you or anyone else knows a better way to do it, I'd like to
learn it, since this transmission and engine are going back into the car
when I get finished rebuilding them.

Ed

I think it will be a Getrag gearbox.  Easy enough job if you know what you
are doing.

I would try to get one out of another 325, as the gear rations may be
different for other engine sizes.

I am thinking about picking up a 1989 325 convertiable that needs a new manual transmission. What transmission would I need?  would this be found in a lot of other
models like a 320i or a 325e.  Is this a real hard project?

I also have a 1983 320i  and need to replace the drivers seat. Are there any other bmw
models that have seats that will fit in my car without any modifications.

Thanks,

Woody         Tyrone Ga.