Sounds like fun, if the other projects are G Scale related then be sure to post them here. Bill

I agree with Stokerman and there is a parts store sale going on right now and the part shows available.  A simple test is to remove the rear drive shaft and run the loco if it does not bind you can run it while you wait for the part.  Loco Bill

Glad you got it going.  I presume it was a quartering issue as you expected. How did you modify the bottom cover to accommodate the Version 5 gearbox? It is good to know that the Version 5 Motor and gearbox works on the older units.  Thanks Bill

H Rob, I agree with Greg, it is like buying a 20 plus year old car and putting a new motor in it, hoping nothing else fails. Go for the chassis. Until someone tries to do that fix you propose, we will not know if it works, so chassis replacement is still the best way to go.  If you want to be the one to try buying the version 5 parts, you could cut a hole in your bottom cover to clear the gear.

Have fun, Loco Bill

Well if you want one check this out. Its for parts, but I will bet the motors and drive train are just fine, Bill

https://www.ebay.com/itm/287653150333?mkevt=1&plmtId=1100001&mesgId=8604729843702962499&mkpid=0&emsid=enull.m164382.l178272&mkcid=7&ch=osgood&euid&bu=43149770531&trkId=717229e9-7dcc-3492-a4b4-f70999389c27&cnvId=375debb5-2944-4697-a3db-a4f8bb676c5d&cnvCtxId=02e3ce37-f254-47c0-ae0d-55af87f80a63&osub=-1~1&crd=20261017014726&segname&recoId=287653150333&recoPos=5

I hacked one of mine into a Boxcab for my Colorado & Kansas Railway and had fun doing it.  The frame and Trucks are a perfect base for the kind of hack you want to do.  In my case I did leave the sidrods on my bash.  I am sure You will have fun  too. I battery powered mine and hardwired the power from the receiver directly to the motors on the trucks.  Plenty of room for everything inside. 

I have two and they are great runners. Bill

No the boards are not in the parts listing. 

He bought The GP 40 so no other coupler available.  AFIR only the 1:20.3 locos came with the Bachmann Offset coupler G88012.

Bill

Hi Kurt, So the main problem is you are using a 1:29 locomotive with a body mount coupler to pull a 1:22.5 scale passenger car with a truck mounted coupler.  Now basically this is not what they were produced to do.  Having said that You could convert the passenger car coupler to a body mount coupler or you could use a Kadee offset coupler on the passenger car truck mount to gain height.  If you do this with one end of one car creating a conversion car you can use it to pull the rest of your 1:22.5 equipment without changing the rest of them. Leaving the locomotive as is will also allow it to pull the 1:29th scale cars that were designed to be used with it should you wish to get some.

Hope this helps,   Loco Bill

Robert,  I forgot to mention that many Bachmann Large scale products made in the early days 1989 for example were sold in Department stores rather than Hobby shops selling trains to enthusiasts.  While there were no production numbers many times these items ended up in the trash, damaged or destroyed by crazy kids and so became more hard to find.  Back when I was a kid my brother and I blew up some American Flyer freight with fire crackers just to see what happens   , and also shot some up with BB guns .

In the end value is what you are willing to pay for an item you really like.  Care and research will get to that point.
Have fun, Bill

That is a tough Question. Bachmann never published quantities unless it was for a special run, and even then they were not consistant.  Way back awhile they released over a period of years The Golden Classic series of Large Scale Train sets.  There were also some limited edition freight cars, but some of them were rereleased again years later, so not really limited .  If you are buying on Ebay, a Bachmann item described as rare it is most likely the dream of the sellers If you are after an item and wondering if it was limited tell me what it is and I will give you my best guess I do have the numbers on the Golden Classic sets. 

Cheers and Beers, Loco Bill

You are most welcome. So the last batch was produced in 2011, and stayed in the catalog until 2017.  They remained available at dealers after that for some time. Unfortunately for parts purposes your climax was run in 2011.   When Bachmann manufacturers a locomotive any parts for it are made at the same time, when they run out they run out.

Hi Mark,  I am guessing your set is the Bumble Bee Set 90032.  If so your quest is complete.  There were only the three cars in the yellow.  The coach the combine and the full baggage.  It was and is a great set!  Loco Bill

Hi Paule, Your locomotives are indeed very old, and parts to repair them are almost impossible to find and the online wiring diagrams on the Bachmann Site are for the newer versions.  I do not normally recommend conversions for them because they are either Version 2 or three chassis and the those drivetrains do not hold up if they are run very much. I recommend using only version 5 chassis or for more trouble free running after conversion. 

Having said that well cared for older locomotives are converted successfully. Click on this link to a Youtube about converting and older loco similar to yours to Railpro.  https://www.youtube.com/watch?v=f-vsADKAMlo

There are other YouTube examples as well.  Hope this helps, Loco Bill