I have an old r138 DP PCM dual conversion 1024 receiver and want to replace with a 129 DP pcm 1024 receiver are they both the same? and what is the difference? the old one is channel 55 are they both the same as long as the new one is high band?

Yes, The 129 is just a 9 channel, it work with any 1024 pcm system

Thanks, I thought so but was not sure