Just one I haven't tried. The clarifier in this radio was a 10k pot, with a tap for the TX side at about where 2500 ohms should be. The receive side is the wiper contact. Both are connected to ground through the TX/RX relay.
If you can trust the Sam's CB-148, there should be a yellow wire that feeds voltage to the pot, and a white wire with an orange stripe that connects to the wiper. It doesn't say what color the third wire is.
If I was doing a clarifier mod here I would disconnect the unknown color wire and connect the white-orange wire to ground. Then I'd check if the 14MHz crystals were still on frequency in both TX and RX and adjust the various crystal tuning caps until they were. With the clarifier centered the whole time, of course.
I have no idea how much slide range this would give, though. Or even if it would worth the trouble. If I wanted to add more slide I might try paralleling another varactor across D201.
But this all theoretical, since i don't have one of those to try it on.