Lehmans don't need any special diesel antifreeze, just use a good quality automotive. I use the orange Dex-Cool myself.
Where you need the diesel antifreeze (or an additive that accomplishes the same thing) is for the wet liner diesels. The bubbles that can form impinge on the liner and can wear it out. Dry liner engines don't need anything special.
Or is it the other way around? I always get those two mixed up.