Can brake caliper guide pin bosses be replaced, or new Calipers?

[TurnAround]

It occurs to me that one possible source of the steering wheel shudder triggered by 'grab / slip' from uneven deposits at the brakes is that the brake caliper guide pin bosses are worn out, which would allow the caliper to jump back and forth from the uneven deposits.

I'm defining those bosses as: The caliper is attached to the car via riding on guide pins. Whats grabbing the pin is a rubber part mounted to the caliper. It has 5 or 6 concentric rubber 'vanes' inside. Stand to reason.. these would eventually wear out and allow play over the steel guide pins. X has 81k on her.

New slotted and cross drilled rotors and low dust pads on order. I'll have the brake apart anyway. Has anyone experienced or heard of these wearing out and leading to play of the caliper? If so, and you agree its a possible cause, can these bosses be ordered and replaced separately (and under the car without removing the caliper to the bench), or does it require new calipers? If they exist, does anyone have a TIS diagram with part number and proper part name?

Thanks guys.

(Once the new gear is on the car, three months goes by, and the 'shakes' are back, then I'll be meeting with the mechanic to start troubleshooting and replacing more suspension and or steering parts one at a time until the problem is dead. For now, I just have to get the high-dust pads off of there. One issue at a time).