Looking at DVLA nomenclature it initially indeed looked like the MK1 and Mk2 were different DVLA 'Models', 260 V8 and V8 260:
200 ZT SE 260 V8
201 ZT 260 V8
202 ZT SE 260 V8
203 ZT 260 V8
204 ZT 260 V8
205 ZT 260 V8
206 ZT-T V8 260
207 ZT (???)
208 ZT 260 V8
209 ZT SE 260 V8
210 ZT-T SE V8 260
211 ZT-T SE 260 V8
213 ZT-T SE 260 V8
214 ZT SE 260 V8
216 ZT SE 260 V8
217 ZT V8 260
218 Not Found
219 ZT V8 260
220 ZT V8 260
... but then browsing through the higher and lower VINs I found some more cars just with model ZT
and random '260 V8' showing up like in this group of Mk2 cars made within hours of each other:
258 ZT SE 260 V8
259 ZT SE V8 260
260 ZT V8 260
The model designation 'V8 260' for Mk2 as against '260 V8' for Mk1 is an indication but not truly indicative as far as I can see. What about the whole bunch of 'ZT' only models??
If it's any use to know, ZT 260 Mk1 to Mk2 changeover occurred early in 2004 in a 2 week break in production from 02/02/2004 to 17/02/2004. The last true Mk1 #216 was completed on the 4th, the other 7 Mk1 cars which also in a part completed state were mostly converted to Mk2. as far as possible (#210 to #218), at least outwardly, and many became publicity or show cars, including #215 which was converted into the first Rover 75 V8 for the Geneva show. The first true production ZT 260 Mk2 was #219, built on the 17/02/2004.
Purely academic interest for me of course over in Holland, but what about the Rover 75 V8s ??
As a matter of fact 'Olive' and I visited he UK for 4 or 5 years regularly using the Dartford crossing after the toll booth's vanished. Me blithely thinking "that's good it's all paid for at long last, so free now". Those with long memories will recall that was said when the Dartford Tunnel and the Severn Crossing were granted Toll status when built. Never heard a dicky bird about it. ULEZ solution?