O.K. here goes. I got an aluminum swing arm from an s4 (2001-2002) and I want to put it on my 620 (2002) to replace the steel one and to have the nicer shock. The s4 swing arm apperes to be the same one as the ducati performance part #69922091a all the hardware looked right so I started disassembling... When I started to reassemble the bike I found some things that didn't quite fit [smiley=huh.gif]. The stock 620 swing arm axle that mounts to the engine case is to long on the outside of the arm; I don't have the one off the s4, but I shimmed the axle from the 620 so it should be fine. I had to grind some flashing off the eccentrics that hold the axle to get it to fit in the new arm due to the increased wall thickness on the aluminum swing arm, no big deal. I got a set of those axle adjustment plates (the things with the hash marks for wheel alignment) from an 851 and opened them up to the proper I.D. for the 620's larger axle. I got the wheel on and noticed a few more things. The brake caliper mounting braket on the 620 has a larger slot in it than the one on the s4 so I should be able to un-screw the one in the aluminum arm and fabricate a larger one but the real head scratcher is the chain guides. They seam to be about half an inch off to the outside of the bike. (the chain's left side plates ride on the ridge of the guide.) I don't know what to do. It appers that the s4's chain is off to the side a bit more than the 620 maybe for increased tire clearance. I could either sand off the ridge on the guides or move the spacing on the sprockets (I don't know how I could do that) or maybe ducati has a different set of guides. Does anyone have any experiance in this or have a senna (I believe it's the same swing arm) I have looked at the obvious stuff like having the wheel and axle miss aligned and had it looked at by my buddies as well in case I missed something and we're stumped. Also if anyone has the plates that go on the back of the swing arm and the eccentrics (the adjuster bolt may be in a different place than the one's from a 620 because I got a set from an 851 and they are.) that hold the axle and wanna sell them let me know. I fabed a set of the plates on the back of the swing arm out of steel. They're functional but not as pretty. If you read it this far thanks I just wanna ride my bike.