They won't have one to sell you anyway, Loud Technologies bought SLM, but are not interested in selling commodity electronic parts.
This is just a 25 amp 400v bridge, nothing special. KBPC, GBPC, in fact most any bridge you can find with 2504 in the number will probably spec out for you.
Look at Mouser stock 625-GSIB2540-E3 Make sure the legs are in the right order, check the data sheet. it is a 25A bridge, inline wire leads, comes in 400v. Looks like it would fit.
Is there not room to mount a regular old square bridge with the four posts and then run four wires down to the circuitboard? Nothing wrong with doing that when you need to.