It is interesting to note the both Fluidampr and ATI list the 4bt in their diesel dampers. They are the same part numbers as the 6bt but they have added the 4bt to the list of applications. Both companies make similar performance claims. The Fluidampr unit is 9.75" in diameter and weighes about 23 lbs where the ATI unit is just a fraction over 8" in diameter and only weighes 11 lbs. I know several members have used the fluid type and found it does help. Curious if anyone has used one of the ATI units.