DO-41 and other ancient JEDEC packages are quite loose in their dimensions. Though 0.45mm is out of spec.
It might be actually a plastic version DO-35 or the like. Or just straight up cheaped out. I certainly wouldn't run them at full current. Mind, I'd also be suspicious enough to test them for voltage (if you apply a low current i.e. <1mA, they should avalanche stably, getting quite hot in the process but not failing outright -- if you don't have a 2kV+ DC supply, just turning up the (AC) voltage somewhat past what you need for a given application, and checking for reverse current or excess heating, should be good enough. They will most likely cook off shorted if you go too far, use a fuse and it's fine.
Tim
P.S. Consider more descriptive titles in the future, like this one. A "?" about diodes could be anything and no one has any way to guess until they click on it.