OK, it is a crystal! Oscillates at 2017.88 kHz on my tester. I can't see that the X1141 and 958 numbers on the top have any relation to the frequency it works at.
Presumably, there was a B4 crystal holder or holders in the equipment and selection was made by a flying lead. The freq may indicate marine band but also older military kit, something like the early numbers of the Wireless Sets range?
OK, so we know what it is but what does it belong to!?
73
Roger