I'm a beginner and I don't think the ebook was much help. 

Thank you for replying

Would that be your #60302 or #60306 locomotives?

Mr. Bachman
After much research, I now know that my GP40 locomotive is from your HO Special Forces set #00652.  And the body shell is held down by two opposite screws under the fuel tank.  I also believe that this unit is analog or DC only.   

Can you provide me with any assistance in recommending a DCC locomotive that would accomodate this shell?  I'm willing to make minor alterations if necessary to existing shell.

If so, is it possible to have sound as well?

I currently have a Bachman GP40 DC loco that I was hoping to upgrade to DCC w/sound.  But I'm being told that Bachman doesn't make this loco with sound.  Can anyone give me advice on what Loco's this shell would work on?  The current shell is held down by two opposite screws under the fuel tank.   

Thank you everyone.

Question: 
Are these shells interchangeable between different brands? 
Or should I stay with a Bachman loco to insure that the shell fits correctly? 

I recently purchased a Bachman Military camoflouged locomotive #4098 on ebay (item #120337162946).  It looks exactly like my EMD SD40 in design, except that it is 1 1/4 inch shorter in length, only has 4 fans on top, and only has 4 drive axles instead of 6.  All other features look to be the same except for the design of the fan grills and upper ventilation panels (same location different grills)  The difference in overall length is due to the shorter length design of both the front and rear porch.

Can anyone tell me what model of Bachman this is, as I would like to upgrade this to DCC?  And because of the tight interior design, it looks like I will be forced to exchange the shell to a new DCC unit, rather then adding a dcc decoder. 

Any other information would also be nice to know about this unit.
Thank you for your assistance!
   

I have a Bachman EMD F7A Locomotive, is it possible to convert from DC to DCC /sound?  Also can you tell me how to get the shell off? 

Several years ago I purchased a Green Bay Packer collector train set from Hawthorne Village.  It came with a Bachman HO EMD F7A Locomotive that in DC powered.  Can anyone tell me if this locomotive is capable of being upgraded to DCC?