looks like the Land Rover Range Rover had a CHMSL as soon as 1989

https://bringatrailer.com/listing/1989-land-rover-range-rover/
https://www.carsforsale.com/used-car-dealer/rideway-preowned-auto-sales-charles-town-wv-d667315/inventory/details/70005699
https://www.luxsport.com/1990-land-rover-range-rover-county-c-602.htm
https://bringatrailer.com/listing/1991-land-rover-range-rover-15/

I won't list everything i found about pre-1994 ones having it but i think its just too much for being an owner add-on.. or they all had the same idea..

https://www.imcdb.org/vehicle.php?id=1311188
Thanks to karkidbut for finding this