At least Cheney was trying to get work for Americans.  :-)

Because it's their company, and they don't want to.  And, a lot of brass, which is the most expensive stuff, comes with no couplers.

I think lanny meant to say the use of the tuner and metal wheels reduce the rolling resistance 300% so it does roll easier, and I agree on the reducing, but I have not seen that great a change.
You do not have to use metal wheels, but plastic does seem to crud up a lot faster, and I have found they are also frequently out of round.  I got a 4 car set from Roundhouse and 75% of the wheels were bad out of the box,  I called them and they already knew there was an issue, and were quite happy to send me replacements and extras.  I have never had a problem with KD or Intermountain wheels, but I just like IM better, probably because of the more machined look and all metal.

Is this like the 0-8-0, kind of a plug and socket affair?  If so, what I have done in a similar situation is to get some good black nylon thread, or 2 pound test monofilament fishing line is perfect, and basically tie the plug into the socket.  Slip the line thru the wires from the back side on each half, plug together, and draw the line tight and tie a knot. A drop of strong plastic cement seals the deal.  When you need to take it apart, snip.  You're out one foot of line off a 100 yard spool.

Or, some decoders like those from QSI and, I believe the Tsunami, are dual-mode, meaning the decoder will sense whether or not the system is DC or DCC and run on either with no adjustment required.  I guess LokSound does too since my PCM Y6b runs fine on DC, and I believe that's a full blown DCC decoder, not just a sound chip.

The conversions are not that difficult IF you are familiar with what is required to build any Bowser steam engine.  You have to put the frame, valve gear, and rods together, with rivets where required.  You have to file and de-flash the castings.  You have to paint it.
Having said all that, it's an excellent cheap fix for most especially the Santa Fe 2900 Northern (even the ones labelled for CB&Q), since there are no other available models of that loco that I know of.  The end results that I have (I redid an older pancake motored Bachmann J) or have seen run quite well.
It is no where near a "drop-in" however.

It's been slow lately.  I suggest pistols at dawn!  I can bring my own pistols (and I'll be glad to loan you one too, if you need it Sheldon). 

Walthers has no plans to offer traction tired replacement wheelsets for the older P2K locos, even at a price, as of my last phone call about a month ago.  And, they had no spare traction tires either at that time.  I think I am going to see if I can find someone to do a bunch of wheelsets for me on a lathe to fit Stewart Enterprises traction tires.  I am not home and do not remember if the 0-8-0s wheels are very close to the 2-8-8-2s in size or not (I think they are).  If you want to get some done also, please email me, and that may factor into the cost.  (No one will be obligated to anything until I get a cost per wheelset)

One more note.  The Stewart Enterprises traction tires can be adapted to just about any engine with grooved drivers with a little effort.  Clean the groove, use the right size tire, glue it in place in 3 places with either ACC or Goo (much more difficult to not make a mess), and then trim it down until the outside diameter matches the driver.  A needle file cleaned very often works well in my opinion.

I have been tempted to get a lathe and groove my locomotive's drivers that do not already have them more than once.  I still have one old Rivarossi Y6b with trimmed down flanges and the traction tires are still fine.  Just don't get oil on them, and glue them in place and they are fine.

Metal tires are not new; all brass steam engines have always had them as much as I can recall.  PCM just points out that they have cast drivers with metal tires.  Actually, traction tires are usually installed in a groove that only encompasses part of the width of a metal rimmed or tired driver, and not all drivers on an engine usually have them; generally only one pair.  Traction tires are usually made of an elastomeric compound (rubber or plastic) rather than metal.  The coefficient of friction between metal and said elastomeric compounds is greater than that between metal and metal, thereby yielding greater tractive power.
Different types of metal tires can give decidedly different results. on the same (nickel silver) rails.  Shiney plated drivers usually benefit from a decent break in period.  The apparently die cast drivers on the early BLI N&W Class As were very good for traction (and paint), but they went to a shinier version in later renditions for better wear or so I am told.  Athearn's old sintered wheels got better traction that the newer ones, but also collected dirt quicker, in my opinion.
Some people hate traction tires.  They go on about how they come off and do this or that, and they are not prototypical.  (Like little electric motors powering steam engines are prototypical).  Some people like me think they are great, that you have to look real hard to even spot them, and that if they are correctly done there are almost zero problems (in 30 years of using them).  BLI was giving people a choice, which was perfect to my mind.  Everyone is entitled to their own opinion, obviously.
In my opinion, PCM can get by without traction tires and still achieve decent performance due to their weight, but I still wish they had provided a spare traction tired set.  P2K earlier on, and Athearn could have greatly benefitted from traction tires.

I do not know which tender you have, because Bachmann does not designate a tender as the "long haul" tender that I am aware of.  The advice above is as good as I can muster.

If it is dragging between the trucks, the size rail has little to do with anything - something is hanging down to far or something has allowed the trucks to seat too deeply.  Possibly something not fully seated properly or a design error needing sanding as alluded to above.

Well said Sheldon.  I have a bunch of their passenger cars but only 2 locos.

To the best of my knowledge, the Allegheny is ONLY available lettered for the C&O.  The C&O is NOT the only road that rostered them.  Therefore an undecorated model would be preferable in my eyes to one lettered for the Virginian, as 1) I believe I can do as good a job with a set of MicroScale VGN steam decals than, or 2) a better job for less money on their part, and they don't have to do anything except get blank numberboards made and NOT decorate some of them.  That should address the 3 year delivery time to get anything changed/altered.  3) There are freelance modelers who might want to roster one.  Therefore I will never understand why a manufacturer does not offer undecorated models.  You CAN get an unlettered Big Boy by the way, and UP was the ONLY road to run those.

Reverse the polarity just on the off chance.