4x6 speakers can be trimmed. wait, some if not most of them can be. i have a infinity 4x6 that sits in there, not held on by screws (the screw points had to be shaved off. but it wedges in there nicely.

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198? 300D ???K - Future DD
1989 300TE 285K - traded in '12
1984 300SD 186K - Sold in 08
1978 300SD 330K - Died in 05