In the layout process it was determined that the speaker's best location is the center of the lower tender's pan. The pan will have to be modified for this speaker placement; holes will have to be drilled in the pan to mount the speaker and to allow the speaker to sound properly.
The picture above shows the pencil lines that were traced on the top of the pan to show the exact placement of the speaker and the four mounting holes of the speaker's flange. With these added location points and the stock features of the pan in this area, a template was created out of 1/4" graph paper. The picture below shows the finished paper template being placed on the bottom of the pan so that all the location points of the holes can be transferred to the bottom of the pan.
As can be seen the template has a fair amount of holes for the speaker to sound properly, but makes allowances for the stock features such as the mounting areas for the brake mechanism and reservoir. The template's hole location points are transferred to the bottom of the pan using a set punch and small hammer.
The detail pictures above and below shows the location points of the holes as they were transferred from the paper template. In transferring the points it was discovered that the pan is not composed of brass, but is made from metal. To confirm this, a magnet was used. Yes, it stuck! If this pan was made of brass then the magnet would not have stuck to it, but more important is the fact that brass does not rust like metal will - especially when holes are drilled in it. Since the possibility of this loco being exposed to long, outdoor use in climatic weather is virtually negligible, all I will have to do is dress the holes with a little paint. But, this discovery is passed on so that the new owner is aware. If this loco was slated for heavy outdoor use, then I would have had to suggest that the pan be drilled, sanded down, primed and re-painted completely. The extra service would not have been at any small cost either. It should be noted that the original paint job on the metal pan does not include a primer coat. 
The holes were drilled using first a 1/16" drill bit followed up by a 3/16" drill bit. The pan was placed on a block of wood so it would not be distorted during drilling. The drilling operation was the most time consuming part of the whole process. Taking almost two hours to drill the 80+ holes. The result is pictured below. Please note the miss-aligned….Ah…I mean handcrafted speaker holes.
The final step to this part of the process is the actual installation of the speaker. The speaker is mounted using 4, 1/4" 4-40 screws and nuts. To avoid "speaker rattle", I usually use a small bead of sealant on the speaker edge to help affix it to plastic surfaces, this is not needed on metal because the metal surfaces are flatter and good contact is attainable.
The picture above shows the installed speaker.