As this car was originally special order from a high rank General during the 60's we joked about the craziness of the general to special order coupe as per his taste - regardless the cost. Perhaps Mercs were crazy enough to fulfil the order as long as being paid. This maybe one option though.
What general in which army? it cannot have been european or American military or even south american because it's RIGHT HAND DRIVE!.
Generals in the commonwealth Armies don't have the flashy accoutrements so common to US ,soviet and Asian Generals and a british general in those days would have had a Daimler or similar.
I would say then that it was either built in South Africa or England on a W111 floor pan ,hence the finny speedo and cowl. W108 panels fit a W111 pan because they are the same car under the skin.
It wouldn't have been built in New zealand because the cars were incredibly expensive (we owned them from new) and wouldn't have been done in Australia because of the prosoviet government inspired laws forbidding most car modifications.
I don't think it's worth $12,000 but more like 4-5,000 because overall condition looks good and it has a certain curiosity factor.
In the meantime heres a Genuine mercedes Concept car.