Introduced: 1969 (by Atlas)
Like the rest of Mehano's nefarious line of N scale diesels, this one has a long and tortured history. Atlas was the first importer (starting in 1969). That relationship lasted up until sometime in the mid-1970s when PMI took over. Sometime in the 1980s, PMI vanished and Life-Like and Model Power became the new importers. Life-Like only offered these for a few years before switching over to their own line of Chinese-manufactured diesels. The Model Power imports were a staple of magazine ads for many years, but they finally vanished sometime around 1998. Perhaps due to all of the conflict in the former Yugoslavia?
This model shares a similar design (and history) with Mehano's equally awful GP40 model. Traction tires eat up 4 of the wheels on the rear truck (making for iffy pickup and an extremely wobbly ride). Only two of the six axles are powered. The cheap 3-pole motor and plastic moving parts turn into a shaking, buzzing monster when current is applied. The paint is terrible, the handrails are huge, the couplers are truck-mounted Rapidos, the pilots are wide open, electrical current is ferried around via wires and the non-directional headlight lights up the entire nose from within. In a word - yuck.
Unlike Mehano's line of N scale Alco diesels (RSD-15, FA, etc), I don't believe this model ever received any upgrades or improvements over its lifespan. My Atlas SD45 is virtually identical to my Life-Like SD45 which is identical to my Model Power SD45 (with the only noticeable difference being the drive shaft - black plastic on the Life-Like and Model Power versions and white plastic on the Atlas).
Circa 1972, Con-Cor started importing a Mehano-made SD45 using this exact same shell. However, it employed the superior (well, relatively speaking anyway) Mehano RSD-15 mechanism (the one with both trucks powered). Those were around until the mid 1980's when Con-Cor reissued the model with a new Roco mechansim (but still sporting the same old Mehano shell). Those floated around until the late 1980's when Con-Cor ultimately dropped all of their Roco/Mehano diesels.