Knuckle coupler for Black Widow

[en4cer]

I have the Bachmann Spectrum F7a and b Black Widow Southern Pacific set and they have the rapido couplers on them. I would like to convert them to knuckle couplers but I don't know which couplers to use. There seem to be so many out there these days, how do I choose? I do have the Kato Santa Fe El Capitan passenger cars that are equipt with Kato's version knuckle couplers so I would like something that would match well with those cars. Any help would be appreciated.

[Franz T]

The F7's use a Micro Trains # 1128 coupler, it is a very easy conversion..