If the switches are still in there, they've been pushed past the smoke unit block and into the area behind it.  I have no intention of using the smoke unit.  I've retained them in a couple other lokies and find I just don't bother using them.  Were they to emit a lot of Black smoke, that might be another matter.  (G) 

Since last post, I checked diagram again, which confirmed the smoke box front is a separate part.  I just returned from the basement where I easily removed it.  It revealed that there are no switches remaining, so they have been removed.  I do see the big, square block under the stack which would be the smoke unit.  It is, "cocked," a little to one side, not sure why.  Under and all around behind it I see a mass of colored wiring and a glimpse of what I suspect is circuit board. I've been convinced for a while, (like you now suspect), that it has been over-sprayed to matt black.  The spot plate, which I think came with no road number, has a, "27," decal nicely applied.  Same on the sand dome, and a, "C&S,"  under the cab window.  All nicely weather over to eliminate a stark appearance.  I looked at all the Bachmann site catalogs applicable to these and found my stock number shown for 2002 and 2004.  "Painted, (black), unlettered.  For 2006 no all black shown.  Can't remember a out white or silver smokebox.  But 2002 and 2004 was all black. 
The date code on the box of November, 2000.  If this model was introduced in catalog year 2001, as mentioned earlier in this thread, all this makes sense as they probably were building them in 2000 getting them ready to ship for the new sales year.  Also, our late club member, Russ,  who had this was a never married, well off financially fellow and left this world with a house full of model RR equipment  in all scales.  So for him to have purchased this when it appeared a new Bachmann model for sale, makes sense as well.  Furthermore, we have had a couple excellent craftsmen in our club who did a lot of work for members.  Good chance that is how my model got, "modified."  I'm not unhappy, as this sits it is totally undamaged in every mechanical sense, and all parts are as they should be.  I'll just put it back in service as a well worn but still beautiful model. 

Thanks again, Fred.  The smokebox door was not hard to open although the little hinges are delicate as you noted.  I hadn't thought of trying to pull the whole smoke box front off.  I'll check the diagram and see if it is shown as separate first.  I see the empty switch openings inside the smokebox on what I seem to recall is called the petticoat sheet.  (If I remember my firing days right......) 
I really like the old girl;  being almost flat black, I suspect it was over sprayed that flat by previous owner. 

Dug a little more on this dating concept that intrigues me so much.  I looked at two Spectrum OS frame 2-8-0 boxes.  NO codes at all inside the flap.  I looked at my 2-4-2, ("Lynn" type), and it had K110426.  Now that is apparently, 2011 - 4th month - 26th day.  i.e. April 26, 2011.
Next, my Heisler was code:  031028.  So it would be October 28, 2003.
Now........back to my 2-6-0:  I'm thinking the C01107 I reported earlier must be a sloppy stamp and is really 001107.  That would put it at November 7, 2000.  And that fits with Loco Bill saying these Moguls appeared in 2001, so mine having been made in November of 2000, is reasonable so they were ready to ship as a 2001 model.
Why the Consolidations have no codes stamped in the box is a mystery.
Otherwise, this whole dating thing is shaping up. 

Next,  -  Loco Bill:  Thank you for the reply.  Yes, I will try to download catalogs from the Bachmann website.  I won't open up the locomotive until I've done all the homework I can possibly do...first.  I'm trying to be really careful.  The previous owner did leave me a couple mysteries however.  One, the smoke and NMRA switches inside the smokebox cover are not there.  Two, inside the tender there is a round speaker attached with clear goo, probably silicone.  Neat enough.  The speaker is owner wired out the back to a 2-prong male plug obviously meant to attached to a trailing car.  Speaker wires do NOT go toward the locomotive at all.  All other wiring inside the tender is for bringing track power from trucks to the two factory appearing plugs under the front lip of the tender frame where the lokie pigtails plug in.  I'll need to convert this locomotive to battery and probably sound, as I have no layout but lots of friends who do.  And they are all battery.  Good time is when I'm into the motor/gear problem.  Likely use ZIMO.  I will be leaning a lot on your tutorial, loco bill.  Thank you again.  I found I had purchased parts a few years ago and I see two axles with brass gears, one I marked 25-tooth.  I also bought and have NWSL individual gears.  Again, thank you.

Thank you both.  Very helpful.  First, wraujr....Yes,I do have the original red box.  I just looked inside the flap on the end that has the model information.  I see,   "CO1107"    I'm trying to fit that with the manufacturing date code you described.  Can't quite get it to fit.
Ideas? 
Actually, I really like things dated, - for a lot of reasons.  This tip you just told about is a complete and very welcome surprise.  I had no idea these could be dated.
However,  I'm still confused with the code I see stamped inside the flap.
??

Thank you.  I had found that, but only clicked on a couple of the first 4 listed.  Those are apparently for the light industrial Mogul, not the Spectrum I needed.  Now I see the last three listed are what I needed. 

About says it.  I didn't get the manual or any docs with this used Mogul.  Looking for tips, disassembly visuals before axle swap.  Thanks, Dennis

I have a Spectrum G 2-6-0, Item No. 81492, painted, unlettered, black.  Got it from one of our club member's estate.  Won't run; motor spins.  I have replacement axles, (one with brass gear), but before I get into it, I'm curious if it is an early/original version, or if Bachmann upgraded these with model changes over the year.  Any way to tell?  I did find the nice Loco Bill tutorial for this repair.  Thank you!!  Associated photos for the article seem to be now unavailable - wish I had them.  I also got no manual with this engine - any available on line?  Bachmann website does not seem to offer anything.  Thanks, Dennis 

Another group answered.  Yes, it does, (and did), pop off by lifting up.  Thank you.

This ought to be easy.  Got my new On30 little Heisler.  Does the factory installed coal load and, "fence," remove by just pulling up?  Parts diagram suggests that but I am so careful with the little fella, I don't want to force anything.
?? 

Just ordered a single, (one in one box), tank car, p/n 27198.
Also ordered a pair, (two in one box), tank car, P/n 26521.
Huge difference in size. 
Why? 
Both billed as On30.
Just differences in prototype railroad build size? 
Nice cars;  like'em OK.  No problem there.
I don't understand size difference.
Thanks for tips,
Dennis

Thanks.  I've had new trucks sitting here for some time now.  I think the most interesting, (and frustrating), detail so far I've described in my other post here.  No need to type it twice I guess.
Great info here;  thank you all.

Answered my own question.  I have one I purchased in 1998.  Incandescent headlight bulb.  8 screw plastic trucks.  Does have chuff contacts.

This is a followup from my recent post regarding early production/version 2-truck Shay chuff contact question.  Respondents suggested removal of the cylinder set.  Some before me had discovered the secret to removal were the two hour-glass lobes-on-posts visible inside the firebox.  Bachmann's concept was the lobe being hour-glass shape would fit through a mating keyed hole in firebox, and once inside the lobe could be turned 90-degrees or so, it's screw tightened and that became part of securing the cylinders to the locomotive.  With the screws loosened, ( and that requires an off-set Phillips and patience), MY lobe would not budge.  Worried I'd break it.  What was I missing?  Interestingly, I'd bought a brand new cylinder set from Bachmann months ago.  I grabbed that to see what it would reveal.  Yup, lobes-on-post were there.  Loosened screw, tried turning.  Not a chance!!  Felt like it was all welded in place.  Could not see any parting lines in moldings.  Also that is a long screw in there; part of what holds the cylinder base molding together.  So back to my project Shay.  Mind you, I've got 3 or 4 hours now fussing with this.  One lobe on my Shay was already positioned to exist the keyway.  Other nearly so.  Hmmm.  Wonder if someone's been in here?  (Used Shay)  So only one requires movement....and only a few thousandths of an inch.  Finally risked breaking it and turned harder with long-nose.  Got it to move just enough to get cylinders OFF the loco.  Whew.  The short story and answer here is that all of these on my two cylinder sets were so dry and tight, they were locked stuck.  I put a tiny drop of plastic compatible lube where each lobe-post met the rear of the cylinder base and waited a while.  Got brave and with parallel smooth jaw pliers, began working them.  Each produced a faint, "squawk, then came loose.  Worked them all free.  So some day, some of you will encounter this.  And since I've viewed every, "tips," and youtube helps I can find this week, None mentioned this.  Hope it will help one of you some day. 
Second, the reason for all my efforts is because in rebuilding my Shay toward DCC, I'd checked continuity with a VOM on every wire in this locomotive looking for the chuff contacts.  NEVER found a pair that revealed make-and-break continuity as I rotated the cylinder drive lines.  Never.  Now that I have everything out I see that my chuff contacts are not working at all.  Pulled cylinder heads off - and they work.  So I'll have to play with re-tensioning/bending springs until it becomes as reliable as I can make it.  PS:  my NEW cylinder set shows continuity ALL the time, so it will have to have attention some day too and be adjusted properly.