I went through the worry about this a few years ago, and thought that the guys at Bavarian Engine Exchange (used to be Roundel advertiser) also did gearboxes, even recall an exchange quote of $2800 for the 6 sp. Don't know if still true or I merely had a dream - mine was replaced by BMW under extended warranty (only had a weak 2nd gear synchro and they changed the whole thing for a new one). BTW, the new synchro never seemed really much better after all either - and I'd checked that there is at least a new case in my car.