The 4 original TRX glow plugs were:
3230 - Hot - supposed to be best for the pro .15
3231 - medium - supposed to be best for 2.5 & 2.5r
3232 - medium - supposed to be best for 3.3
3232x - medium super duty - supposed to be a long life 3232
info compliments of an old thread. joint effort from...