I don't think my DII has ever had that ran through it.
And what is thebest recomended way of using it?

 

Wal-Mart, AutoZone, NAPA, Advanced Auto Parts just to name a few.
Buy two cans, there is a vacum line that goes into the intake plenum, I believe that Disco2Guy has a nice pic of the line to use, start the truck and stick the end of the vacum hose into the can of SeaFoam. Let the engine suck it in. Once the can is empty shut off the truck.
Use this time to clean your throttle body with a spray can of carb cleraner, use the whole can if you need to.
After 15 minutes start the truck back up and drive it around, put your foot into it once or twice to really break the carbon loose. Lots of smoke is normal while using the SeaFoam in this way.
The other can, go to the gas station, pour the can into the gas tank and then fill up with premium and drive until the low fuel light comes on.
Make sure when you do this that the truck is properly tuned with no mis fires.

 

https://landroverforums.com/m_78005/tm.htm

 

Wal-mart carries it for 5.99. Other places like Auto-Zone charge up to 8.99!

 

...and park away from the house...think about what a lot of smoke looks like...then multiply by about 3 or 4x. But it's normal.