Thanks for your comments.  I was hoping to stay with a prototypical coupler size since it would be larger and presumably has better allignment tolerence between opposing couplers (smaller is tougher to maintain).  I would also like the option of mixing rolling stock manufacturers.  What is the advantage of swapping out Bachmann couplers with Kadee #5s?  Is the knuckle larger on Kadee #5s and closer to the typicle 9" high coupler normally used on narrow gauge?  Will #5s match up with Bachmann engine gear boxes.  Is the resulting height and fit of #5s compatable with Kadee 803s?  I appreciate all your feedback.  Its like a first time computer buyer.  One can spend a lot of money only to find out there was a better direction to taken . . . Swiny

I am just getting statred into On30.  I have collected a large amount of O scale (Lionel, MTH & K-Line) equipment over the past 4-years, but never created a layout because of a growing concern about the look of three rail track.  I am now looking to sort out all of my questions before pulling the trigger on a change.

Your On30 engines and rolling stock come equipped with E-Z Mate Mark II couplers, which I presume are the same as HO couplers.  Since On30 this is 1:48 scale, can I easily convert the couplers to a product with larger knuckles such as Kadee's On30 or O guage couplers?  Will these fit into your existing gear box without a major retrofit?

Thanks . . . . Swiny