Don't guess.

 

Most of the 125T and 170T heaters have this Ignition Control board. Part number 104068-02

Some of the 125T & 125T heaters have this board which has a digital readout and 4 LED lights. Part number 116111-01
 
If you have a 170T heater and you are not sure which board is in your heater- pull the board and look at it. Compare your board to these photos.

Don't guess.

If you guess and order the wrong board you have thrown your money away because there are no returns on these sensitive electronics.