Agreed, I know a J chassis code (1988), with "turbo S" in the V5 UK Reg Doc, is Red / Black Sports 8 way & split rear seat, no sunroof, 10 speaker, diff, wheels, 928 brakes, M44/52, M030, but has not build code M758
The TTM definition AND the 944man definition are both correct in my opinion.
Martin, the bling'd car was "your car" and money no object it could be again. I'll throw an idea to you at risk of going off at a tangent. There is a Safire Blue, 1986, 220 car, non-ABS, for sale on the forum with a diff. Its far more original and I think if you drove it - the less is more appeal may ignite. Its lighter weight, better made in terms of original forged rods and maybe a bit longer in the etch primer tank at the factory (IMO) but it has a sunroof as they all did in UK spec. It has a proper spare wheel too. (ever tried collapsing a space saver after inflation?[8|])
I dont know the seller, and have no axe to grind but the car strikes me as a really genuine, original one, low miles, with the benefit of an unusual colour. It will appreciate in value - you heard it here [

]
At the end of the day, the turbo Cup ran for '86, 87, 88, 89, and then changed to the Carrera Cup when the 911 lost its torsion bars [

], so they are all Cup Cars at heart.
Just a thought
good luck
George
944t