There are a bajillion LEDs of all sizes, shapes, and colors on amazon and ebay. Pick one that is compatible sizewise, then measure supply voltage and choose a limiter resistor accordingly. Or get fancy and get a voltage converter with an adjustable current-limited output.
Without knowing more about the scanner, assuming it is 12 volt is a bad decision. I have a scanner that runs on 2 AA batteries, and I seriously doubt that the voltage is converted up to power a couple of bulbs. Most modern portable scanners use 4 AA cells, and 12V is not likely to be correct. What you really need is a schematic for the scanner to give you correct values.
Or you could measure the supply voltage going to the bulb, given that many Uniden scanners do not have publicly available schematics.
Also, if the supply voltage is less than 12V but greater than the forward voltage of the LED, the LED will still work, it just won't be as bright as intended. All you need to do is choose a diffrent limiter resistor to get the desired current:
The OP made no mention of "portable" scanners....he specifically referenced tabletop/mobile scanners...."9000, 895 ,898t." A quick check with a multi-tester would reveal the voltage supplied to the original lamp and a replacement plan could be developed from that point.
The BC895XLT and BC898T use a 9 volt regulator to power the display lights. The BC890XLT powers the lights from a 5 volt regulator. These radios all have circuitry to switch between bright, dim, and off. LED's can be substituted for the lamps if you understand how the circuit switches the lamp current to control brightness.
I have found a lot of 8 volt wheat lamps but can't find my spares from Uniden, need the length/ diameter of the bulb any help ??
BC895 9000, 898t, pro2022,2006 AOR TR4500, pro 2042, pro 2052, IC rx7, BR330, several other uhf mil scanners. Lot activity hear in eastern NC.