Do I need to use sealant, and secondly the orifices are labelled differently.
You would not want to use sealant on the orifices. If you use sealant you take the risk of clogging the port for the orifice.
How do I find parts to change it back from lp to ng or tell if it was ever converted flames always seemed to high and very hard to regulate temp.
To tell whether the unit has been converted to LP you would look at the regulator cap and see if it shows Lp or Nat. If your serial number begins with a 10 to 38 then the orifices are adjustable and if the unit is converted to Lp you would loosen by 1 1/2 turns and close the air shutter to where it is about 1/4 open for all burners including the oven burners.