Not done it but I did consider it a while back. My mate had the 2l td in his sprinter, when it went bang we managed to source a 3.0l or maybe even 3.2l from a sprinter ambulance. It towed car trailers brilliantly and didn't abuse the fuel too much.
I cant remember what he did to it but he played about with the engine affter the swap and my god that thing shifted...