Hanging rear caliper

[Mike Del Tergo]

I did the swap today. I peeled back the intact puck boot and found the puck 
to be fully encrusted in rust.  From surface type rust at the furthest 
extended surface to solid (immobilizing) rust closer to the caliper.  I have 
swapped quite a few calipers but have never rebuilt one, but my guess is 
that when you pull back this boot there should be some amount of lubricant 
or brake fluid to prevent this rust?  Of course I would have thought the 
outer boot would also have prevented it but not in this case.  I have also 
never seen an instruction sheet on a "new" caliper call for any preinstall 
prep for this surface? Hopefully mystery hanging caliper solved.
thx
Mike