I was thinking of the PM 4018 RC Set, these though in later days supplied with all plastic track had metal wheeled chassis that could be converted to track pickup with relative ease. If I were to do this I would also put metal wheels on the coach end bogies to give track pickup to all wheels. A superb running set would then result. With a repaint these can be converted to a very nice littke train as has been shown on these pages.
View attachment 218196
Of interest there is more than 1 version of this and 4011 is another that I quickly found this morning. The following picture is a random conversion I found on a google search.
View attachment 218197
JonD