If there is a zirk fitting or bolt(where a zirk fitting would go), you could hit it with some grease, and change it out later. It is basically up to you and what you want to do.

W/o the boot the joint is exposed to the elements which will cause it to wear out sooner, but with everything still tight, it isn't something that has to be done right now.

More than tread lightly. Leave it like you were never there, nor anyone else.
'90 X-cab 4.88's 33 BFG AT's, rr ARB, Headers, Ignition upgrade, cold air induction.
'91 X-cab 5.29's 315's BFG MT's, rr ARB, custom bumper and flatbed