Its original routing location is up past the frame to the radiator support. It got mounted to the drivers side radiator bracket up near the headlight.
The frame isn't really high enough if you encounter any kind of water. Even running in the rain can cause it to receive moisture, and that isn't a good thing when it comes to gear oil.
Might be a good time to drop the gear oil out of the front end and do a lube change. At least then you would be sure that it doesn't have any water in it. And make sure the end of that vent tube is mounted up as high as possible, out of harms way, with a vent tube end in it.
'87 YJ, 4.2L built and bored, 8.5" of lift, 8.8 rear, AX15/NP 231, Tom Woods drive shafts, Flat fenders, 12,000LB winch, Custom bumpers, Rattle can paint job. Never completed...