Rare indeed. Same motor and same ZF trans too in the Lincolns. I've dealt with a few in Bimmers and seen _one_ still alive in a Ford, ran good but the air suspension was shot. Pretty neat though, Ford cared enough about making it look legitimate under the hood that they invested in a different valve cover for the Bimmer diesel, complete with a Ford logo cast into it! Must have given the original engineers fits when they saw it...
Nice motors, quite similar in design to the VAG/Volvo D24T, same displacement, OHC six with an aluminum head, several decades' worth of development ahead of the old MB 616/617 design. Both the sixes run very well, quieter/smoother/faster than an equivalent Mercedes, but both are fragile in terms of the cyl head and gasket... Volvos can be retrofitted to an updated MLS headgasket that is a major improvement, I don't know whether the BMW motor has something similar available but I guess not. The Bimmer has a crossflow head that is good for an extra few HP versus the Volvo but makes working on the injectors, glow plugs, IP, etc more difficult. Both are uncommon enough that they are not the easiest to get parts for, but the Volvo is easier than the Bimmer, in part because of its number of common parts with other, more pedestrian VW and Audi motors. Biggest challenge with both is finding someone competent to work on them. The cars are rare but people willing and capable to keep them going are rarer still.
The Bimmers I dealt with both were neat vehicles but in need of fairly significant work and with owners that were trying to find ways to keep them on the road, with limited success. Basic maint and even IP timing adjustment on one of them was pretty straightforward but that was as far as I wanted to get involved... and as far as my equipment would take me anyway. If you're excited by the idea of having one and are OK with learning to wrench on it or finding a mechanic who wants to work on it, and has the right special equipment and knowledge to do it effectively, or is willing to climb the learning curve for you without making you broke (good luck!), then I know of one near me that is in need of help but mostly solid with an owner that would probably sell...
Otherwise better off with a Volvo, a Mercedes, or a TDI with an 09A...
