One of the guys in my club is using a line lock as a parking brake, I am not sure how much I would trust it though. I would be worried it would leak down over time. I work in the oilfield so I don't trust valves to work as promised as much as most
![Wink ;)](https://board.marlincrawler.com/Smileys/marlin/wink.gif)
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If it was me I would look into the transfer case parking brake. I trust something mechanical over longer period than I would something hydraulic.