No, the glove box does not fit with the defroster vent installed
BTW the heater puts out very minimal heat due to the size of the heater coils, at high speed water passes through the coils to fast to put out any serious heat in the cab if you are counting on it to stay warm and when 500/520 is at idle the engine does not stay warm enough to produce any heat either....have a look at my little red moose build for a recap, do yourself a favor and buy the glovebox and a diesel heater and rig it through the back window if you are looking for some serious heat, as a defroster it should work for plowing....how well...TBD, winter is on its way here in Canada.
Both myself and a buddy back east installed the inferno in our machines late winter/early spring and both of us experienced same operational issues and came to the conclusion.....warm weather heater not intended for serious cold Northern US states and Canada get. He did put some cardboard in front of the engine rad which did make the heater run hotter but at what expense to the engine as our buggies are cold blooded machines. the manufacture even confirms this in one of their install videos....good luck, my money would have been better spent elsewhere and is the least favorite item of the upgrades I installed.
Just my thoughts
Railrunner