This is an excellent original revolution counter from a 1958 Jaguar Mark IX saloon. It is in good working condition, clean with nice face, bezel and casing. The needle works when the input shaft is turned and it is free and smooth, so we are betting it could be used as it is.
This instrument is designed for external illumination. However, it could be fitted with internal bulbs in the bosses at the rear with slight modification, and then it would be applicable for a Jaguar XK 120, 140 or early 150 (later cars has a clockwise-operating rev counter).
We have lots of other Jaguar gauges, including XK, Mark VII, VIII, IX, and E-type/Mark 2.