You can’t go wrong with Kadee #5, though I am moving to #58 for all of my new installations.
I, like VAPEURCHAPELON, have discovered the Sergent couplers. I have about 10 cars and two locos equipped and a friend and I tested them on a modular layout and were impressed. Impressed enough that I will not buy anymore KD, McHenry etc. They cost about twice as much as a KD but IMHO, they are da bomb. And in 15 years I think that we will see KDs and clones becoming what the ‘hornhook’ is today. Now for me this is not a big thing as my cars and locos are packed away as I do ot have a layout and this can be phased in. Those with layouts would find changing much more difficult.
Kadee #58s all the way, EXCEPT:
They work decently with #5s, but you will run into some trouble in some instances (like layouts with small radii). Unfortunately, it doesn’t look like Kadee will introduce all of their shank options for the #58 size. So, a great many certain locos that require longer shanks can still only be #5s. It would be nice to get an extended shank #58 so I can put it on my Athearn sd40-2s with their snowplows. Just can’t do it with standard #58s. It’s too short… and too bad!
But those little scale size 58s are cool (they look right), and do force you to achieve near-perfect tracklaying. A great challenge.
No. 5 is more reliable in tight radius coupling. I do have some #58, but for the 18" radius at home, #5 is the way to go. #58 are a little fussier,but look nicer; #5 works in most situations without aligning drawbars (more user-friendly), but is slightly oversize.
For the Athearn SD40-2 with plow (RTR), take the factory plastic POS plow off. The mounts are in the right place for a Details West #155 plow. Paint to match, enlarge the holes slightly, add the plow. A #5 or #58 with the trip pin cut off will work very nicely. Less deflection with 100 cars on it.
I believe that the best couplers are kadees for functionality as well as fairly prototypically correct. However I have some cars which have kadees on one end and a mate-matic on the other. This way I can couple to cars that don’t have kadees. Mate-matics work fairly well except when you want to uncouple them. Most of the time it seems that you have to pick one of the cars up and twist it to get it loose from the mate-matic.
William
Birmingham, AL