Yup, the load resistors for the turn signals (which you will need to buy), but you won't need to be too concerned (read on).
Since the new lamps are LEDs, they draw so much less power that the SJB will think one of the bulbs is burned out, and it will flash the signals faster. Do a search on turn signal load resistors, and see if you can find any that are encased, or at least designed to handle the load without melting anything around them. Also, since these will be used only on a separate turn signal feed, they won't get anywhere near as warm as they would if they were used in place of a combination stop/turn signal.