Right, your all a bit off.

While the Mk3 Escort was out, and the XR3i, Cabriolet and RS Turbo were all current, Ford did a limited edition run of "All White" XR3i Cabriolet's. These were stock XR Cabs, with spcial trim interior, and had full S1 bodykit (no decals).

THERE WAS NEVER A CABRIOLET TURBO RELEASED BY FORD.

So the listing IS bollox - the All White bit is right, the turbo bit is bollox.

Onto Custom an Non Custom RST's...

All S1 RST's were "non-custom" from standard. Think of the Escort Cos and you could add the "Lux" pack which gave leather, Air Con and CD. This is what the Custom pack was to the S1. Basically all you got tho was electric windows, central locking , opening rear quarters, and a Sunroof (possibly sunroofs were standard on all custom and non custom, this I am not 100% sure about - tho there are S1's without sunroofs that haven't been re-shelled)

So again, the Non Custom bit is correct. But not on this car - thats bollox. All White Cabs didn't have a Custom pack option.

Later when the S2 was out, there was a limited Edition cab called the All BLue - limited edition interior + S2 body kit...