Spray dull coat recomendation

I use Testors laquer Dullcoat.

Second on the Testors.    I'd also recommend following other's recommendations that you spray Testors Gloss before applying the decals.

I used the Micro Scale Industries products,  Micro Sol and Micro Set for decal application after the gloss coat.   

I followed these steps and got great results.   After the decals fully cured and I was happy, then I shot the car with a final coat, maybe 2 light coats of Testors Dull Coat.   

I use other cheaper matte clear coats for buildings, but not on freight cars, and especially not on a car that I spent so much time doing decal work on.  Just not worth the potential savings. 

Like Chris said, there are cheaper alternatives like Rustoleum 2X  Matte Clear and Krylon Matte Finish that I've used on large structures where detail is not quite so critical, but I use the Testor's Dullcoat on anything important, including final decal sealing.

Tamiya or Testors.

If you painted it, its wise to use the same brand of clear coat that you used to paint it, to reduce the likelihood of any sort of bad reaction between the layers at the last minute.

If its some kind of factory paint, you can probably spray on anything.  The hobby cans, while more expensive, tend to leave a much better finish than the home depot cans, so consider that if its something you have a lot of time and effort invested in.

Big thanks to all the  info.....joe

........Rustoleum 2X  Matte Clear

I use this on everything; decals and dry transfers.  Just enough and no more - light spraying.