"I am assuming you have a 10 speed looking at Trek's page for the bike so this Shimano XT RD-M786-SGS or Deore RD-M6000-SGS would work fine"

I destroyed my RD today with a a not so elegant landing on the table top. twisted beyond repair, tweaked the chain too, and it will need replacement. I cannot find the shimano m5120 long cage anywhere online. My cassette has 46t, and neither of these listed seem to allow for 46t... I'm a bit new at all this, so don't completely understand the compatibility with the two mentioned. Not sure an upgrade is worth it for me, just looking to replace with similar. Thanks

UPDATE:
After doing some research, I found a SLX M7100 which seems to be very similar match, and a slight upgrade. Fit perfect, not too much calibration needed either... after re-viewing some YouTube videos got it installed. I bought a new chain too and had to shorten a few links without a chain break. (ended up grinding down pin on one side and using nail-set to punch through). I also had a shard of the dorkdisc stuck in between the cassette and spokes which would not allow the freehub to move, once that was removed everything works great. Back to the trails.