1st Gen R53 Cooper S Transmission failure?

Sounds fun! So the transmission is user serviceable? I mean, even unofficially is fine as long as I can find parts. =)

 

So I think Jack Nicholson may be right...I had tested the shorter drive shaft by pulling the wheel end loose and rotating it to hear the gears in the transmission move, but I never did that on the other side. Well today I was pulling it apart again to drop the trans. I compared the drive shafts; The short ones matched, the long ones didn't. The one that I ordered and installed seems shorter from the bearing carrier bracket to the transmission. I don't know if you can see it from the pictures, but only like 1/16th inch (or less) of the thread was contacting anything inside the transmission. The part that was was ground off. I guess might have been what I heard when I first put it all together and tried pulling it out of the garage? So...I'm going to order some of those drive shafts that you linked, Dave, but is there anything that I need to know as far as options? I mean the one that I got looks almost perfect, the bracket mounts up, the splines seem to be the right amount to fit, but the length was just a bit short. Did I get a non-S version or something?

 

Is it relatively straightforward to remove the bearing carrier from the old and put it on the new?

 

Interestingly enough I found out, from a thread on another forum, that all I needed to do was switch out the bearing carrier from my old drive shaft to the one I had bought. So...as much as I would love to spend $400 for a second set of new drive shafts as advised, I opted just to use the ones I had already bought. Thank you everyone for the help.