STS-51D
The STS-51D crew wore the standard AB Emblem embroidered mission emblems on their flight suits and on their in-flight clothing, thus there is no rare 'crew patch' for this mission.
The history of the STS-51D mission patch begins with the insignia of the STS-41F mission. That mission, scheduled for launch on Discovery, had a crew of five whose names were arranged around the body of the patch.
The STS-41F mission was cancelled not long before the scheduled launch and a series of crew reassignments and orbiter and payload changes followed. Eventually the original crew found themselves scheduled to fly again on Discovery with two additional mission specialists added, making it possible to reuse the original STS-41F insignia with just an additional name tab at the bottom.
This allowed AB Emblems and Swissartex, who had apparently already begun manufacturing patches for the STS-41F mission, to re-use these patch bodies for the STS-51D mission with sew on name tabs at the bottom.
Note that as far we know no Lion Brothers patch was ever produced for this mission. Also, no vintage Cape Kennedy Medals version has been identified.
Embroidered Mission Patches
A-B Emblem patch
The AB Emblem patch was the version used by the crew. The patch has a separate name tab sewn on at the bottom.
Swissartex patch
The vintage version of the Swissartex STS-51D mission patch exists both with a waxy plastic backing and with a vacuum sealed clear plastic coating on the reverse. The fronts of the two versions are virtually identical.
The patch has a distinctive thick merrowed border added around the body and sewn-on tab of the patch.
Swissartex later one piece patch
The later version of the Swissartex STS-51D mission patch was made in a single piece, without a sew-on tab.