That is essentially a 4 bolt 104mm BCD crank, however the large chainring is the spider/mount for the middle ring.

The only thing weird about it is the large chainring. You can find them fairly easily, sometimes the prices are a little high as it's somewhat unique and short lived.

The Shimano LX and XT from that generation are interchangeable, so you could use either large ring if you found one. Also the large ring/spider can be replaced with an optional 5 bolt 94 BCD spider to take standard compact drive rings.

I might actually have an extra one of those large/outer rings around here somewhere.