What's the difference between the two listed on Wiggle? Long cage and long cage PDI? Shimano website lists GS and SGS, and one is Shadow RD+ ?
Is it some kind of direct mount version? Used to be available in 10spd, dunno about 12
Longer cage one for 1x12, shorter for 2x12 with smaller rear cassette?
8100 vs 8120?
8100 is 1x12, 8120 is 2x12.
8100 comes in SGS and GS one is for 51t the latter for 45t cassette's, 8120 is a different model/shape typically for 2x. As for PDI haven't a scooby doo
Ask them in the Q&A thing?
I'm pretty sure it's a CRC thing (e.g. packaging/OEM) rather than a Shimano thing, going by public Shimano information. Perhaps CRC had some stock set aside for replacing derailleurs found damaged during pre-delivery inspection of complete bikes.
That could be right.
I’ve seen Nukeproofs delivered marked as missing drivetrain and brakes with those missing parts shipped in an accompanying box. Whether that’s down to spec flexibility options, or duty avoidance (may not be seen as a complete bike, so subject to lower duty rates?), or another reason I don’t know, but as above would possibly explain the PDI term.
Noeff is correct re model differences.