Do not have that adaptor. Our Pioneer speakers come with short hardwire pigtails that can be easy wired to the origional wire. I know this migh be a issue for some but that is the way it is. A word on the poliarty +,-. Is always nice to know which one is positive but if this is not easy to find just keep the hookup the same ofr the pair. Meaning hold the connect in you hand and use the wire on the right side for the positive on both the left and right side wires.
If you are replacing your truck speakers with new aftermarket ones, the factory termails are not going to be of use any more unless you are wanting to put them back and remove the new ones. So cutting them off is no big deal. If you are not allowed to cut, try using quick splice wire connectors that do not require wire cutting