It will work in most cases, as both do not have an integrated diode in them anyway ( datasheets do indicate this if present, and give specs on them, typical device is a BU508 and BUu508D, one without and one with the diode and otherwise nearly identical as example) and are otherwise going to be driven the same in both cases.
Check before replacing why the old one died, they normally are the symptom, and typical causes are open circuit or high value resistors in the base drive ( yes that 10R or so resistor in the BE path is needed, along with the other resistor across BE junction), dry joints on the drive transformer, dry joints on the LOPT ( resolder all of the LOPT joints, they often hide the cracked solder joint under what seems to be fine looking ones), dry joints on the film capacitors ( and on a multisync monitor there will be a few of them and some high voltage MOSFETS switching them into circuit that can also have dry joints) and otherwise just dry joints in the area. This is the one area where a bipolar transistor is still king, other power devices ( other than Sony and those so disliked and now unobtanium GCS thyristors they designed) simply were never robust enough to survive.