Hi,

I have both models of the 555 and I can not tell the difference by looking at them, therfore, I had to write the model numbers on a label and stick it on the case. As far as I know, the only sure way to know is to try them with the different transmitters (JR is positive shift, Futaba is negative shift).

I know this will not help you now, but it may help for future purchases. I now buy the Hitec Universal Supreme, there is not much difference in size and the shift is selected by a jumper.

Sorry I couldn't be of more help.

Fly4Fun,

Wayne Miller