To best of my knowledge, as expressed earlier the aforementioned THING is German made. In Germany few RHD Things were produced for european market i.e. UK. In Germany, the produciton of type 181/182 took place in Wolfsburg, Hannover and Emden plants. But in 1971, this particular Thing's year of manufacture, the production was only active on Wolfsburg plant making it one of the earliest Things ever produced. And the fact that very few of the 182s were produced at Germany makes it even rarer. Total German production of Type 181 is believed to be around 70,000 (50% out of total production figures of Type 181+182+Type M181).
I believe and as suggested by the "production plate / 07-5-2837", this type 182 would have been produced in Third week of February 1971 on a Friday. Plz note that the suggested date/day cross matched with 1971 calender - check your PC calenders for 1971 - exact date of manufacture comes to be February 19, 1971.
As I putted earlier, its european market version of type 181 (also known as type 182 for RHD specification) which, if would have come with a tranny, it would have been a Reduction Gear Box unit.