Dorman makes replacement dust boots, not the best but they keep the grease in and the dust out. You need the 5/8 boots for the jeep TREs, which they used to sell as single product (13563) but now are only sold in sets with the 3/4.dust boot (13567). Sometimes you can find these at the local autozone or wherever in the Help! section but if you need more than one or two your best bet is to order some from rockauto.com or ask autozone or wherever if they will order them for you.
Jeep also sells replacement dust boots for the original gear. IIRC they are $30ish each just for the boot, about the price for a whole replacement aftermarket TRE.
BTW there are four TREs there with a grease boot on each TRE. The drag link comes from pitman arm to passenger knuckle, tie rod intersects drag link and goes to drivers knuckle.