Two items with around 20% chance to spawn in legendary quality (otherwise purple). Never seen them in any guides.
1) Police helmet with anti-shrapnel visor.
Gig: "cuckoo's nest". Helmet located on second floor, directly between elevator/stairs and cell with mission target.
2) Militech heavy tactical vest.
Gig: "radar love". INside garage with two hatches on roof (one directly behind target vehicle).
Another item is almost 100% spawns as legendary.
3) Loose-fits with micromesh underlayer.
Gig: "goodbye night city". Inside central building, door with very low tech skill check right behind locker with another legendary item (SMG).