High-Low range shaft O ring part number?

Hey dudes, I'm currently rebuilding the gearbox - must update thread soon, and need the O ring that goes on the end of the high low range selector shaft where it exits the 4wd selector case at the front.

I've got a gearbox gasket kit and a seal kit but its in neither - though there is an O ring for the intermediate shaft (it says) which I don't remember seeing on stripdown! That one is much bigger. I can't see either o ring on the exploded land rover diagram or parts list that I've got.

Basically, I'm after a part number for the front O ring if poss and a pointer as to where the bigger o ring (about 1.5") goes?

TRS1013 - it's shown in situ on my parts diagram so it's not obvious.

Awesome! Thanks. Nothing was coming up for that but a bit of google found TRS1013L which is commonly available. I live near bearmach hq so will call in tonight. I've found a parts diagram showing where the bigger O ring goes on the intermediate shaft so sorted on that too. Thanks again.