The first version of this "Military Special Set" was introduced late in 1958. Publicity for the set in 1958 did not describe the locomotive beyond stating that it was the "new double ended diesel locomotive"  The 1959 Canadian illustrated price list stated that the loco was green and orange.

In correspondence with Pat Hammond in the early 1990s the subject of the loco colour came up but, at the time, the single set that had been seen was the 1958 RSX set and it contained a standard blue & yellow R.159 loco. Thinking that someone must have replaced the locomotive the information published in Pat's first book was based on the 1959 description. Since then two more examples of the 1958 RSX set have been found and they both contained the standard blue and yellow locomotive.

After Pat's first book was published  this pristine 1959 R3.S version was found which contained a green & yellow loco, not green & orange and the green of the plastic was similar to that used on the dark green 0-6-0 Diesel Shunter of the period.

Other differences in the 1959 set, other than the Series 3 track and Mk3 couplers, are the colour of the Avro Bomber and one of the well wagons. This wagon also has a non-standard  "43171" number. This was possibly done using the tooling for the R.120 maroon Suburban Brake Coach albeit without the preceding "M" making this possibly the rarest version of the bufferless R.118 Well Wagon which in 1960 received its own designation of R.236 Depressed Centre Car.

Since we acquired this set we have become aware of several other boxed examples and they all include a dark blue well wagon with the 43171 number, however, we have recently been made aware that a medium gray example exist. At this time it is not known if it is from an R3.S set or if they were made available individually.