Nice start

Can't help out on the critter body, but I do have suggestion for color. Since Alaska is white much of the the time I'd like to suggest a contrasting color to the white background of winter. The White Pass & Yukon RR had a nice paint scheme, yellow and green. Something similar.

What chassis is the critter using for power?

Bernd

Thanks Bernd, I'll likely be

Thanks Bernd, I'll likely be using (gasp) an Athearn mp15 (or an Atlas). I think the sound of the 645 will give it a different feel than the S4. I actually was considering white to contrast with the green and brown of the summer landscape, but the point about snow makes sense. Maybe a dark red (maroon?) maybe.

Prime it?

I'd recommend painting the hood with primer to see if the seams are 'correct'. Any defects will be more noticeable.

Thanks, I planned to prime it

Thanks, I planned to prime it once complete, but would possibly having to do a second coat start to make the paint a bit thick?

Great start

Slow Track, nice start on your diesel 'critter'. You know, the only modelers who don't make mistakes are the ones who only model in the mind! Most mistakes aren't 'fatal', just work around the problem if you can. Sometimes a mistake can be turned into an advantage.

I agree that priming and sanding with patience will be worth the effort...and maroon would be a great color, as it would stand out in Alaska in any season.

If you want to capture the flavor of an area you are modeling, choose a name with Alaska place names...or names that suggest the region. I used local 'made up' names for my Estrella & Sonora Grande, which also has my wife's name and children's initials worked into the plan. Whatever you choose, make it fun!

Something like this...

Dear SlowTrack,

As noted elsewhere, take your time with it, and it should come up a treat. The kits are well engineered and go together smoothly if the instructions are followed and due care is taken.

One example, using the S-Helper SW9> On30 conversion kit...
(Not yet completed)

Happy Modelling,
Aim to Improve,
Prof Klyzlr

...

You may find better luck using a wood based filler than squadron.  Just a future note.

Two thoughts

First, on the putty.  I would not recommend wood putty, as (in my experience) it is too coarse for our purposes.  I have started using automotive glazing putty (basically thin Bondo) and I like it quite well for jobs like this.  I will also second the suggestion to prime the pieces.  for large flat areas especially, you will get a much better surface if you use a good coat of primer and then wet sand it back down smooth, until most of the primer has been removed.  Work on separate assemblies for now, so that the primer does not build up in corners.  It looks like the major components of your kit have no louvers or other details, which will make priming and sanding easy.

Paint:  Why not do both, light and dark?  I like maroon, and royal blue is a favorite of mine.  You could have a stripe or other large block of contrasting color, something like the Alaska RR does today, or the picture which Prof posted.  Simple horizontal stripes always look good, and they look even better with a little tweak, perhaps turning them down at to a point at the ends, or up and down into a diamond.  A little detail goes a long way here.

Primer Redux

I'd airbrush on a thin coat to cover the raw plastic. What you're looking for is just enough so that you can see any areas that need correction. Like Ken said, wet sanding until smooth will remove most of it.

I'm looking forward to seeing your work. - I'm really digging those louvers on the short hood. 

Thanks for all the replies

Thanks for all the replies and encouragement guys, much appreciated. As far as stripes go, I don't for see doing that for two reasons... 1 I want this to be a simple scheme, 2 I'm not a great painter. I planned to use a paint marker to prime and check the seams once sanded rather than paint the entire model. Its actually not plastic at all, its thin wood with a covering of a peel and stick material that acts as a skin. Sorry if this post is a bit jumbled, long night at the "office"