The (U)BC144XLT uses the familiar MC3361 receiver IC (IC2). It's the DIL version, which makes connecting to pin 9 of the MC3361 fairly simple

The Uniden Bearcat (U)BC144XLT

Pin 9 of the MC3361 contains the unfiltered audio

• Connect a 10 k or 12 k resistor to pin 9 of the MC3361
• Connect a 2.2 of 2.7 nF capacitor from the resistor's other lead to ground, e.g. to the metal shield of the coil left of the discriminator IC

Close-up of the IC connection

• Connect the inner conductor of a piece of shielded wire to the junction of the resistor and capacitor
• Connect the braid to the metal shield of the coil
• Connect the other side of the shielded cable to a 3.5 mm chassis terminal that you mount in the back of the scanner

Overview of the discriminator output