Rear Diff A-frame pivot boot torn

[J.P.]

Got a torn grease sealing rubber boot where the A-frame attaches to the top of the rear Diff. Anyone replace one of these? Can I just replace the boot. I assume I gotta drop the arm- is it attached to the diff/ball-pin somehow? Shop manual is no help here.
And where do you get a new boot?
Thanks! J.P.