Thank you all
Thanks so much for the great replies, they've been most helpful. I also appreciate the advice given with regards to dealing with the dealership.
For your info, I'm located in Singapore. I've updated my profile as suggested... and you can easily tell I'm a 2-stroke nut! This GS (Chocolate is her name) is my first BMW and I love her to bits.
I'm actually a mechanic by training, I work in a factory servicing turbomachinery. I've always done all of the work on my motorcycles and believe in the old adage, "If you want a job done well, do it yourself." I've just started night classes at the local university and that, coupled with some really long shifts/overtime at the factory leave me no time to work on my bikes. I've therefore had to send them to various places to be fettled...
I've not had very good experiences with the local BMW dealership; I will be honest with you all, I am not a well-to-do person and me and my old GS aren't exactly given star treatment there. The dealership refuses to pay for the damage because my motorcycle has no prior service history with them and in their words, "The previous mechanic must have cross threaded the pivot pin or used the wrong type of Loctite, that's why the case broke."
I am not an idiot, though and any mechanic would know to STOP when dealing with a seized fastener in an aluminum alloy part. I have access to a radial drill so I could have easily drilled the pin out if they had just called me up and told me that the bloody thing was seized and they couldn't get it out.
My primary aim is to get my dear machine out of the workshop as soon as possible, so based on your advice I shall check this matter out with Anton/Ted Porter/Beemer Boneyard.
I may have a good deal on a used transmission from a wrecked R1100RT; it is my understanding (via Anton Largiader's website) that the transmissions on all models (with the exception of the R1100S) are interchangeable, so I shall investigate that route. In any case, my motorcycle has more than 110,000 miles on it so I think it might be wise to get a decent transmission with low miles on it, just to preclude any issues.
I will update you guys when I get more info; I'm quite new to BMWs and I know how frustrating it can be dealing with a lack of information. Maybe we can get some kind of transmission FAQ up and running to help others in similar predicaments.
Thanks again for all your help, ADV rocks!