Can't figure out how I did it (no big jumps lately, all flat land running) but I somehow cracked half of a mounting tab off my 528xr block. I hit a puddle of water while bashing and I think the sudden drop in temperature from the cool water on the hot block cracked it.

So I'm looking for a 528x series block, top/rex/nr doesn't really matter.

Don't feel like buying a new block for $180.