Some Mercedes Benzes of the era used a similar key. Contact your local Benz owners club and see where they go.
Or let your fingers do the walking, call all your nearby key shops.
Razi, if you're questioning whether the key should go into the lock farther, and it doesn't work as is, you've nothing to loose by filing it so that it goes in further. I've had to do this with a copy of my '85 BMW motorcycle key, after two fails by different lock shops.