As described in the Heljan Di3.641 (renumber/DCC) story, the intermediate (mellom) design color was introduced in the early 1980's. In the summer of 1983 I saw the Di3.606 in Mo I Rana. The photo shows the author as a teenager looking at the Di3.
Because of this picture, the Di3.606 has been a special locomotive. My very first model of the Di3 was the Di3.606 in mellom design. This was a NMJ repaint of a Märklin model.

NMJ has made one version of the intermediate design in their topline Di3 serie; the Di3.607. Getting another copy was the start of this story.

The NMJ Topline Di3.607 with a decal sheet with new numbers.

The old numbers are being masked with Tamiya masking tape. Removing the numbers are doing with a grit 1500 Tamiya abrasive paper. This is done wet.

Installing sound in the NMJ Topline models is very easy. They come with an MTC21 connector. It is just a matter of removing the plug and install a new decoder, a Loksound 5 in this case. To make sure the lights are right, I've also removed the wire to the R and Rf positions on the board. See Install an ESU Loksound decoder in a NMJ Topline Di3 for more details.

The end result; a model of the Di3.606.

This photo shows four models in the intermediate (mellom) design:

• Heljan Di3.643 - original production model
• Heljan Di3.641 - renumberd model
• NMJ Di3.607 - original production model
• NMJ Di3.606 - renumbed model