Power Products.
But, seriously, listen to these guys. Before you blow money on a new battery for a radio that old, look closely at your other options. Sinking all this (new battery, old computer, cables, RIB, etc) into a radio that old might seem cool, but at the end of the day you've blown a lot of money on a radio that's 25 years old. Unless you have to have the "Motorola" nametag on the radio, or really need to have "CopSounds®", there are newer, better, more reliable radios out there that may do what you want.