Three ID plates, as seen between the legs of the gimbal actuator arms on the
left of dsc17023.jpg.
The top plate is the engine's "master" ID plate. Although most of the
pre-printed lettering on the ID plate is illegible, the plate reads
Part name: Rocket Engine Assembly
Contract No.: NAS8-5604
Part No.: 104001
Spec. No.: R-1420eS
Stock No.: [blank]
Serial No.: F-4028
The two smaller ID plates are the "MD identification
plate RD171-1022-0001," used to indicate what "MD change"
(engineering/configuration change) incorporated into the engine.