Mike, I have never used the Southern Digital frames before, I have always had the factory Kato frames milled by Aztec Mfg, (now closed and retired) John would mill out just enough for a DZ 125/ 123 decoder and put a small cut down the inside for the lower brush wire so not to be "pinched" when you put the unit back together. I heard that the Southern Digital frames were poured from a softer metal and sometimes warped causing all sort of problems, again never owned one so not sure if true. Parts are drying up on the old unit but can still be found for a good price at shows, I have a box of 25 units that are just for parts(all used) for the fleet that has decoders and have a good stock of Kato factory parts too so I can keep my fleet running.
Gordon Bliss/ Santa Fe-All the Way
