on some cars yes, but not the viper.
there is a 5v data wire in the harness, third pin from the right on the top row. just do not connect this wire to anything and you will have no problems putting in any aftermarket radio.
the CAN BUS on the viper is very limited. all you need to do is not connect the data wire. to anything. this goes for the gen 4 too. all the wire does is send a signal to the radio identifying the vehical. the radio decides if it belongs or if you have to take it to a dealer so they can program it to work with that car.
no factory radio, no problem. just do not connect the wire and its all good.
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