Well, I'm a newbie and not sure of Allante VIN info.
However, I think if you have an Allante with a VR in the VIN and your final sequence is 101827, it means that your Allante is the 1827th HARDTOP built that model-year. All 1987 - 1989 Allantes will have a VR VIN.
A hardtop Allante is defined as an Allante coming from the factory with the hardtop - because starting in 1990, the Allante could be delivered from the factory as a soft top only, which made the VIN a VS, not a VR.
And the final VIN sequence for a soft top VS Allante is in this format: 12xxxx. You don't have that sequence format.
My original post above is trying to verify if that VS format actually begins at: 125001. Meaning that if a VS soft top Allante was the 1500th car built that model-year, the VIN would be 126500. But I'm still waiting for verification.
Hoo boy, this is confusing! But stick with me.
My explanation holds true EXCEPT for 1993, when ALL Allantes were VINed as VS factory softops, which means a 12xxxx format VIN. However, if a 1993 Allante left the factory with a hardtop, the final VIN sequence stayed as the hardtop 10xxxx format.
1993 factory soft top: VS with VIN sequence 12xxxx
1993 factory hardtop: VS with VIN sequence 10xxxx
Kinda confusing, but I hope my non-expert suggestion helps!
By the way, I think your car would be a 1987 - 1989 model-year with that high of a hardtop VIN sequence. I don't know production figures for 1990 - 1993 hardtop Allantes, but I don't think that 1827 HARDTOP units were VINed in any model-year in those later years. Maybe an Allante expert can tells us those specific production numbers.
Again, I am a newbie.