Most of the big manufacturers make dozens of rectifier types; these often fit generic specifications. You really want a device type; failing that you need the voltage (1kV), nominal current, single cycle in-rush current, reverse recovery time and so on, in order to find something that fits.
I think you need to ask the guy who did the upgrade for more details.
The one I picked out is probably going to work; it is big enough (35A single cycle current, 1A continous) to handle the likely in-rush current at turn-on. But if there something weird about the circuit, or it has a very big reservoir cap, you might need something more exotic.