All three of these decoders use the 21MTC [21-pin] format. We highly recommend using 21MTC decoder with the Nix Decoder Buddy motherboard: https://tonystrains.com/catalogsearch/result/?q=nic%3Dx

For general DCC applications we suggest using the 58429. The 58419 & 58449 are for users with Motorola or Marklin systems.