Looks more like an aluminium housed resistor, the thing Stackpole Electronics is/was good at.
If it is a capacitor, it's a 1% accurate one, MKP or better.
hermetically sealed cap with mounting studs. whether its a feedthrough type can be found out by measuring between the wires with an ohmmeter. this cap was most likely made for military equipment. the solid mount would keep the stress of the weight of the cap off of the wires.
