Way back in 2001, I bought MTH's Premier EMD FT 103 demonstrator set, 20-2277-1, which was sold as an A-B-A set. While it's a super set that runs, sounds and smokes great to this day, it was not an accurate depiction for the real FT 103 that had two B-units, for an A-B-B-A arrangement, when it debuted in November 1939, shown here.
Over the years I thought about buying a different road name FT B-unit and having it re-painted to match the 103 demonstrator paint scheme, but just never got around to it. Then in 2015 MTH re-releases the FT 103 with separate sale B-units, so I'm in! After some delay, they're finally delivered in August 2016, and I order one sight-unseen, 20-20623-3, below.
I was concerned a bit on how well the 2016 paint scheme would match up with the original 2001 FT set. However once I placed the new B-unit with the original A-B-A set, the paint was a virtual perfect match. The original B is the foreground and the new B is in the background. Looking at both in even lighting, it's hard to tell which is which.
So now I have a full, complete A-B-B-A set of EMD's FT 103 demonstrator set from 1939.
But there was one snafu however with the new B-unit - it does not come with a jumper / connecting 10-pin tether to connect the two original A-units together, despite the image shown on the product page. So after searching the MTH parts pages, I eventually figured out what PN I needed to add (don't have that PN right now though) to the new B. I needed a cable ~ 12"-14" long with a male plug on one end, and a female plug on the other.
Adding it through the new B was no problem, after taking off the shell. The male plug side simply pops into the female plug on the end of the original B-unit, below.
The other side was not as basic. Since the new B doesn't come with a tether bracket to attach the female plug to, I just zip-tied the male plug from the A-unit to it's coupler shank, to keep it elevated over the track, and then just plug it into the new tether on the new B-unit, below.
This new hybrid A-B-B-A FT 103 set works like a champ, and looks pretty cool pulling a long string of freight.