There were three completely silver VX's made, well I mean silver coloured and silver painted cladding, they are recognizable by their black oem wheels and leather upholstery.
If yours doesn't have these trademarks, it's a "self painted one".
By a converted tank you mean, an extra tank for the lpg right?

Check the front rotors (Jap version ones need to be replaced quicker )
Check if the monitor works in reverse.
For more not Jap version specific VX problems I'd like to refer to the serarch option.

Good luck!