I would check with Parker-Hannifin I believe they make a JIC fitting that locks. If you are near a big distributor of Parker fittings you may get a quicker answer. Parker has a humongous number of fittings.
Another company that may have a locking fitting is Imperial but I can't locate their website. Probably gobbled up by somebody.
Need more information from you regarding JIC 37 degree fittings, such as: size (example -4, -6, -8, ie...) and what are your application pressure requirements?