For the late 1980s the Bridgestone Klimatic got a major make-over. The basic design now incorporated SunTour's signature, and excellent, dropped and slanted parallelogram. Finally this looked a very good device, but by this time Shimano had established SIS as the de-facto standard, and no one (except Bridgestone) was interested in a cam based system.
Interestingly the indexing mechanism means that the adjustment screws have been moved to the front of the derailleur (as on the original SunTour Competition). Long ago this design was abandoned because the screws tended to catch spray from the front wheel and rust solid.
This is a short cage version, with a straightforward pulley cage, but with a huge offset. I believe that this basic design was introduced in 1986, but I think that this particular, dark grey, look dates from 1990.