This is clearly a plunger-picketing sprocket slide-shackle from a late-series Mark 4 Thronomister. The crocketted ogive and fillialled corbels are typical. However, since it lacks the retaining-ring bracket and keyway for the auxiliary drive-shaft flexible-coupling unit, it is from a pre-1992 unit and has not been modified to the updated specification which gives greater output downstream of the upper bypass-duct turbulators and greatly reduces the prevalence of harmonic vibrations in the vortex-aligner section of the primary flow-retarder stage.
This component bears all the marks of being made by the Dale-Parsons Manufacturing Company of Bessemer, Wisconsin, and was probably produced in the late 1980s and stored, hence escaping the mandatory upgrade program for all in-service units. Alternatively, it may have been sourced from an aircraft being parted out in one of the boneyards, also escaping the upgrade due the long-term storage and a possible discepancy in stock inventory control.
The condition as photographed suggests is is not capable of re-manufacture or other forms of recyclable-aviation product rejuventation or rehabilitation and should therefore be tagged as scrap.
Complete (but time-expired) units regualrly turn up on eBay, but the postage is usually greater than the value of the profuct itself and as such they attract only the unwary.