As many of you went through this, several years ago our Denso-made navi systems stopped working. Denso put out a disk to reprogram these units, but it did not fix mine (did fix a Corvette at the dealership with the same problem), the problem just got worse and now my navi system is pretty much dead. Here is my question...... Did anyone try replacing our GXP unit (US4) with one from a Corvette (U3U or U4U) and did it work after getting the VIN coded to the unit? I have the Monsoon system and HUD, so the unit has to have the subwoofer and HUD attachments.