The photo above was sent to me by the same friend that sent the Geometry Slug photo, I am not sure where he found it. My guess railpictures.net.   In any event this is another unique slug to me and I immediately was ready for the challenge.

NS Slug 921 was formally a GP 9 with the NW railroad, road  #844.  In 1985 it was rebuilt into the 921 road slug, model RP-E4D. There were several of the GP 9's converted between 1984 and 1985, many were setup for remote control, Slug 921 was not.

As price dictates a lot of what I do within the hobby I set out to find a couple of used GP9's with dynamic brakes. 
As it turned out fellow club member and friend David Ward donated a pair of undecorated GP 7's with dynamic brakes. 
Close enough for me! 

I had already assembled about every image that I could fine of the #921.  I had also done quite a bit on research on them as well.
The main question was, would they be powered?  Unfortunately this version of slug is very low as compared to a regular GP9.
I'm not giving up just yet but it will be very difficult to pull off. Once the shell is completely built and ready to prime I can begin
working on the motor and chassis to see if this can be accomplished. Its not looking good even for an N scale decoder at this point.
There is no top weight to remove, the current engine and control board sit pretty high for this slug.  The weight is molded into the frame steps, fuel tanks  etc.

Let the cutting begin.  The GP 7 was completely stripped of all glass, handrails etc.  The cab was also removed as there would be no cab.  To be honest not even the current vents would remain.  One of the first problems that I ran across was that Atlas molded the dynamic brake tubes to the shell. I had really hoped that they would of been removable as there were on some earlier Athearn GP 40's.  

On the slug the Dynamic Brake tubes were moved up to the front end of the locomotive.  I carefully cut out this section from the GP7 using a band saw. Once this section was removed the shell was marked for height reduction.  The band saw was again used.  The problem for me was that both sides were not being cut in the exact same places.  In other words one side was cutting more off than the other.  There is no guides for custom cutting a thin locomotive shell.  You basically have to hold the shell real still while you cut.   I quickly abandoned this process and went to plan b. Using an Exacto knife, the shell was cut in half on each end.

With the shell split into two halves it was much easier to reduce the height of each side.  Sounds crazy I know.  No turning back now. Once the two sides were the correct height they were re-glued as one. To strengthen the shell, 3 small pieces of sheet styrene were cut then glue in between the shell sides.  At this point both the sides and the dynamic brake section needed to be trimmed, sanded etc. I recommend using a band saw as little as possible.  Once trimmed correctly the dynamic brake section was refitted up in the front area of the shell.  Notice in the photo that the top piece of the front nose was still missing.  The section was cut out by hand then adjusted with an Exacto Knife and sand paper until it fit back on top of the nose and in front of the brake tubes.

To complete the roof structure sheet styrene was cut then fitted over the rest of the top area on the shell. This was easily done by tracing the shell outline on the sheet styrene.  Once the glue was dried on the top section, sand paper wrapped around a thin file was used to blend it in with the shell sides.  To remove the existing GP 7 vents, a Dremel tool was used.  The vents were sanded down smooth.   Later two sets of vents would be added to different locations. The Dremel tool was also used to sand down the steps area around where the cab used to be.  That area would need to be smooth for the next step.

Removing the cab left big gaping holes in the side of the shell. Again using sheet styrene custom fitted pieces were glued into place to cover all areas left empty.  The only hole left to fill was on the backside of the brake tubes. Three pieces of styrene were cut and fitted here. Once piece to cover the back of the db area and the two additional pieces that angle back down to the top of the shell.

Once all of the panels and or panel opening had been fitted it was time for a coat of filler. Using regular household spackle, all of the cracks were filled.  A couple of coats of primer followed with a light sanding in between each coat.  These steps were repeated until the sanding marks, cracks and or joints were all smooth again. One of the nice things about totally hacking up an HO engine shell or boxcar is, most folks couldn't see any imperfections if they looked right at them.  HO is just small enough to hide a few things yet big enough to get back on the tracks after a derailment.   However I do plan on getting this judged so I will have to spend some extra time on the body work.

 

"Frankintrain"




"Frankinslug"

 

As you can see from the photo to the right there actually wasn't any weight. The two motors sat in the middle with a gear/driver wheel on each end. I removed the gears from the drive wheels to allow for free movement.  In the event I decide to add power to this they can be added back. 
For now though this will be a dummy slug (which is kind of what they are anyway).

The second photo shows the frame after I pulled out the hacksaw, chainsaw, Dremel tool etc.
Actually the hacksaw and Dremel tool equipped with a metal cutting disk were used.  The frame was locked in a large vice flush with the rails so that I could not cut down into the part of the rail that I didn't want to cut into.  I made that mistake when building the #34 Geometry Locomotive, and totally ruined the frame.

The 3rd image shows the frame in the vice as I continued to work on the frame until the shell fit snugly into place. As you can see most of the front area had to be removed to allow the narrow slug shell to fit into place.  No more stairs, cab, tool boxes etc.

As expected with that much heavy cutting you cant help but to leave large scratches, and groves in the remaining metal frame. I wouldn't recommend this to the novice modeler or the faint of heart. Always keep in mind what the end result of each section should be, not how bad it looks at the time.  As evident in these photos almost anything can be repaired.

My favorite Bondo or body filler is household spackle. Using a small piece of sheet styrene as an applicator a couple of coats were applied over the scratched up area. Actually it took three coats of filler to the get the frame smooth again. Between each coat a light sanding was done before I could apply any primer. Unlike real Bondo or body filler household spackle sands much easier and smells a lot better!  To sand I used 220 grit very lightly.  A couple of coats of primer can cover any marks left by the 220 grit sandpaper provided you rub lightly. 

The fuel tanks will need to come off to wrap up the frame work. This proved to be challenging as they are molded metal right into the frame.  It took a combination cutting using our band saw (not a metal blade) and a hacksaw.  I started by slicing the tanks into small sections.  I used the hacksaw for this.  Once the tank was diced up into sections, I  began sawing the best that I could along the frame edge. I made the cuts this way so as to make as accurate a cut as I could.
 I knew from prior experience that trying to make one long cut would more than likely lead to the saw blade curving in one direction or another.

Again I used the hacksaw as long as I could until the saw handle was hitting the front of the frame. From that point I used the band saw which I lubricated with oil as it struggled to cut the metal.
I guess some guys would have stopped at that point, drove up to Lowes and purchased a metal cutting band saw blade.   Not this guy, where's the challenge in that! Besides I was done before I could of went to Lowes and back.  Forget that the blade is probably totally trashed now.

Notice that one of the two air tanks was spared while the other was removed with the fuel tank.
The fuel caps on either side were grinded down next.  To finish off the rail I measured and cut a piece sheet styrene to run along the frame.  This piece of sheet metal finishes off the frame while hiding a few small rough areas under the frame.   Once painted black this will look very much like the prototype.

On both ends of the frame (pilot) the bottoms came out like a step. On the prototype these plows were almost totally flat. Using the Dremel tool and metal disk these areas were grinded flat with the main plow area.  This area will eventually have the black and white safety stripes. I will create decals using Paintshop pro for this. I have done this in the past for a couple of switchers, so I have a couple of templates saved to work off of.

After

Here you can see the #921 is looking more and more like the prototype. Notice while in the vice the 921 is black and later it is painted brown primer again.  The reason for this is the black satin paint I used either was really old, or didn't mix up well when I shook it, or there was a chemical reaction to the Valspar primer that I first used. The black paint crinkled in a few select spots.
I had to go back with a scruffy pad and lightly sand those areas smooth.  I then re-primed the shell with Krylon this time. (its all a crap shoot with spray cans)  You can always test on a board which I did, however the paint went on an old plastic shell not a board.  So it may have been a reaction to the plastic.

Using Krylon Satin Black the body and frame were painted one more time.

The vents on the slug were pretty much all square louvered vents. A fellow modeler suggested vents made by Plano .  These are close but I decided to make the vents using Paintshop Pro, then print then on sticky back label paper from Avery.  That will give me the exact look and a slight raised appearance off  the side of the shell.

Black and white striping for the front and rear pilots, decal created in Paintshop Pro 8.    Using Microscale 1982+ NS Diesel Locomotive decals, along with 2002+ decals, Slug 921 slowly but surely begins to take on the look of a real working slug.  Slugs have a lot more cables on the front and rear than a regular engines do, so I will have to add several more. 

Once all of the decals are in place securely the railing can be re installed. One thing I didn't account for was the need for longer rails.  Having removed the cab the existing side rails would no longer work. Luckily I had a enough railings to between this locomotive a couple of others for spare parts to make it work.  Other wise I would have to get online to see about ordering something.