I wouldn't worry about matching the exact model number of the battery. Instead, it's more important to get roughly the same chemistry and a capacity equal or maybe a touch greater (if technology improved in the last 10 years, capacity could be greater with modern parts).

Specific batteries go in and out of production. But as long as it's the same CHEMISTRY, voltage, and capacity, it's likely compatible. Chemistry tends to set the voltage, size sets the capacity.

Charge/discharge controllers and algorithms are based on these three bits of info.

In some cases, some chemistries are actually compatible with other chemistries. NiHM cells are largely backwards compatible with Ni-Cd chargers (but not vice versa). It's not good for the NiHM but they will actually take the charge.

The chemistry set the voltage and the voltage and the size set the capacity. Everything else equal, a larger capacity battery is often compatible with an original smaller capacity battery in a given device because the charge current will be lower in relation to the capacity.