VBD2 is closed. Please go to https://vbd3.co.uk instead.

Rivet intact but obviously hand painted over the original white.
Rough as a badger's but the Superfast wheels are interesting.
On such a rough model, why would you go to the trouble of swapping out the wheels?
Is it a super rare find or a fake? The seller is playing his cards close to his chest.

https://www.ebay.co.uk/itm/Vintage-Toy- ... 1438.l2649

Interesting piece and the rivet at first glance looks ok, the colour looks like the dark olive drab which I did have an example of as pictured, it is possible the SF wheels were tried out on this piece but it would need looking at closely in hand to comment further.

It's not anything I've ever heard of, or even heard any rumours of. Furthermore, there's nothing about a trail SF-version on Christian's site.
It may be genuine, it may not be. However, if it is genuine, it seems unlikely that it would be a one-off, and if it's not a one-off, then it's implausible that another example has not already come to light.
The chrome on the wheels could be seen as an indication that they have come from a non-army model. I am also concerned about what appear to be big blobbt ends to the axles on the offside.

Just had another look at the listing. The close=up baseplate photograph (the final one in the listing) clearly shows this to be a repaint.(I think this also explains the white flecks on the model.)