My uncle wants to install a aftermarket HU in his 2002 Impala but wants to retain his door chimes and what not. which harness does he need? GMOS-05? would he get to use his steering wheel controls? how much is it and is there a cheaper alternative?

He doesnt think it has the Bose but there is a small stock amp mounted to the top of the trunk

He doesnt care if he looses the use of his steering wheel controls but wants to keep his door chimes

check metra and PAC'* websites for the harnesses
as for the steering wheel controls he will need an extra harness for that too depending on which HU hes running

He can use the same one I used, a Scosche GMSR09. It can be had for about $50 at Sonic Electronics. He'll retain his chimes but steering wheel controls would be lost. Our cars don't come with Bose systems.