For the JLTV development program, the original requirement called for the A-Kit (permanently installed armor) to resist 7.62mm at 30 meters, along with 155mm HE at 100 meters and 6 to 8 kilogram IEDs and mines. The B-Kit requirements upped that to 7.62mm to 14.5mm (I believe varying by location), 155mm at 30 meters, 10 kilogram mines, and RPGs. How that requirement changed over the course of development, I don't know, but it gives a baseline ideal to work from. I believe the RPG cage is separate from the B-Kit, so one can have A-Kit with or without cage and B-Kit with or without cage.
There was some discussion of the JLTV
back in April.