Reverse gear tranny lock.

[RICKG]

As far as the shield interfering with the lock bracket consider this: the shield "plate" is relatively thin gage matl and can be tweaked slightly leaving a small space between the shield and dash lip. The bracket then enjoys a friction fit when installed. Mine will stay in place on the roughest terrain yet pull out easily if I want to stash it in the jockey box. In fact I don't think I've removed it in years..

[Bretto]

Boot shield makes more sense than splash. I probably heard it called a splash shield once and it stuck.