MTL couplers on Spectrum 2-8-0

The MTL 2004 is desgned to fit a Con-cor Dash-9, not the Bachmann 2-8-0. There is no coupler conversion listed in Walthers catalog for the Bachmann 2-8-0.
Actually, you need a body mount coupler. Walthers lists 1025 "wide angle short shank"; 1028 (for flat cars and goindolas); 1027 "short shank"; and 1022 "low/short profile". One of these would probably be a much better fit than the coupler you are trying to adapt.
In any case, the coupler must fulfill two conditions:
a) it must swing freely to both sides enough to cause no sideways pressure when coupled; and b) it must be mounted at the right height.
If you can achieve this, it will work. The coupler must also be securely fastened - glue and/or a small bolt of pin will do the trick.
HTH&GL

Here are the Micro-Trains conversion charts:
According to the chart, you should use a #2004-1. Is that the same as you have? I'm not familiar with these.
Bill Bill's Railroad Empire N Scale Model Railroad: History of N Scale: Railroad Bookstore: 's Books and Toy Trains: to 1,000 sites:

Yes, an
Bill wrote:
Yes, and I finally got it done. But it's always a visual challenge.

The 2004-1 comes already assembled; the 2004 must be assembled. But they are the same coupler. However, the mounting hole is right between the two holes where the stock coupler pocket goes, so I used a minute drop of CA to hold the pocket in place and secure the mounting bolt.

The 2004-1 comes already assembled; the 2004 must be assembled. But they are the same coupler. However, the mounting hole is right between the two holes where the stock coupler pocket goes, so I used a minute drop of CA to hold the pocket in place and secure the mounting bolt. -------------------------------------------------- Thanks!
Bill Bill's Railroad Empire N Scale Model Railroad: History of N Scale: Railroad Bookstore: 's Books and Toy Trains: to 1,000 sites: