I have been chasing parts to replace Bruce's final drive and drive shaft which are worn out. Until we lubed it on a Workshop Day I don't think it had ever been done. We eventually found a final drive and I managed to score a drive shaft off a mates parts bike. On trying to remove the shaft it was found that the shaft would not clear the end of the housing. In order to remove shaft the swingarm was removed enabling the shaft to be salvaged. Due to the fact that the shaft wouldn't come out I brought home the shaft and the housing for further investigation. Some years ago I managed to score a brand new shaft off Ebay. I tried the new OEM shaft in the housing and it wouldn't go in either, and was actually a worse fit. There are minor differences between the two shafts. The salvaged shaft has different yokes a minor length difference and the end of the shaft tube is not rolled over. I believe I read somewhere quite a few years ago about an aftermarket shaft that required the housing to be removed in order to fit it. There are no markings on the salvaged shaft and the OEM one has the following.
BMW 26 11-1 454 063/01550
WET 27/07
 If the shaft won't fit in Bruce's housing I have come up with three options remove the swingarm housing, grind the U/J yokes to clear or machine the housing. Any thoughts from the brains trust.
Regards Martin.

I could be completely wrong here (early morning and all that) but I always remove the swingarm first on disassembly, and fit the driveshaft onto the gearbox first during assembly. You can't do it any other way. I know this because it's a lot easier to fit the rubber boot onto the the swingarm and then wiggle it on to the gearbox without the driveshaft in the way, but you just can't do it in that order, the driveshaft has to go on first.

Merry Christmas to all, Suzi over the years I've lubed quite a a few drive shafts on various K kronies Bricks. This is the first time I haven't  been able to pull the shaft out of the housing. I normally use a set of padded vice grips and a sharp pull releases it. The reassembly can sometimes be a bit harder if the U/J flops over. When this happens a piece of cord? fishing line looped around the U/J and run down the side of the shaft and taped to  the rear of the shaft keeps the U/J aligned. Since posting I've had a talk to Charlie and he told me there were two U/J sizes and two housings with different shaft outlet sizes. After doing some measurements the housing would only have to be opened up very slightly. There is also a possibility that the salvaged shaft will fit into Bruce's housing. 
Regards Martin.

The BMW K100/K75 2V shop manual downloadable from this site describes the removal procedure as removing the swing arm first then removing the driveshaft. The installation procedure is described as installing the swing arm first then sliding the drive shaft through the swing arm to couple it with the output shaft. 

The u-joint of my Brick's original drive shaft would not fit through the swing arm so I worked with the parts the way Suzie describes; the replacement drive shaft's u-joint could fit so I assembled the parts as described by the manual. Retaining attachment of the boot wasn't problematic during either variation nor was a greater thrill attached to either variation.

All these years of cursing that rubber boot and the awkwardness of working on the driveshaft/swingarm.....

Where's me dremel? 

After running the verniers over everything I only have to remove .5mm to get it to fit in the borrowed housing. Or I could just belt it in with a really really big hammer.
Regards Martin.

I also think the best of those options is the one chosen by Suzi and Laitch. There's no alterations that way. Grinding the swing arm is the least worst of the other two.

Yeah grinding 0.5mm off the swing arm isn't much, but let's say it's 5mm thick, so then that's ten percent. How thick is it, dunno.

I've only taken off a few drive shafts, sometimes the uni joint is firm and sometimes it's loosy Goosy. When it's loosy Goosy, gravity can cause the front to droop down. In those cases I turn it 90 degrees, then it can only swing left/right, rather than up/down, so gravity won't have much effect.

I'm on the side of the 'fit the driveshaft first' army. If the damn thing won't go on with a good push, there's lots of room to swing a BFM* at it. IME it isn't that awkward to get the bevel drive to locate into the back of the driveshaft.

*BFM = big firkin mallet. Once the driveshaft is in, you can drink the contents of the firkin.

Forgot to mention, my drive shafts have come out without needing to remove the swing arm.

Ugh. Sounds like the securing circlips are either missing or very worn.

I'm waiting to see whether the new shaft will go in Bruce's housing, which won't be happening until after the New Year. Charlie also has some of the housings with the larger opening which he is willing to send up for the cost of freight if needed. 
Regards Martin.

Hi Martin.   A great read and an a big thank you for all your research in regards to this.    Boy I am looking forward to retirement.  Lol   You have so much time on your hands.   LOL.   It is appreciated.

Regards Bruce