I have JVC CS-V4625 4 x 6 in the front dash. I'm thinking of using the same type 4x6's in place of the 4x10's in the back pillar. Will I need an adapter to make them fit in the rear pillar or will they fit? Can another size fit into the 4x10 housing (4" or 5 1/4")? My truck is a 1992 GMC Sonoma SLE ext cab. Thanks.