The Mercedes-Benz 450SLC rear deck lid accommodates a 4x6 inch speaker size in that location. Full-range units are the compatible type for the audio system. These specifications cover the years 1973 to 1980.
A single driver that reproduces bass through treble without a separate crossover network. It is the simplest replacement option and is common in factory audio systems.
Additional Notes
The rear deck lid is a horizontal surface positioned at the rearmost section of the passenger cabin, typically situated beneath the rear window and above the trunk compartment.
Mounting in a rear deck lid location places speakers in a fixed, flush-mount orientation facing upward toward the headliner and rear glass, which affects sound projection direction relative to seated passengers.
The deck lid surface constrains available depth behind the mounting plane, as the trunk cavity below represents the only clearance for speaker basket protrusion.
A 4x6 inch oval speaker dimensions indicate a non-circular cone geometry, which allows fitment in locations where a round speaker of equivalent surface area would not physically seat within the available cutout dimensions.
The oval shape of a 4x6 inch driver produces a wider horizontal dispersion pattern along the longer axis, which in a rear deck lid position orients coverage across the lateral width of the cabin interior.
At 4x6 inches, the driver surface area is moderate, supporting low-to-mid bass and midrange reproduction but with reduced low-frequency extension compared to larger round drivers of 6 or 8 inches.
Full-range speaker types are designed to reproduce the entire audible frequency spectrum - typically from approximately 80 Hz to 20 kHz - within a single driver unit, without requiring an external crossover or supplementary drivers.
A full-range driver installed in a rear deck lid position handles all frequencies from that location independently, including upper bass, midrange, and treble content.
The Mercedes-Benz 450SLC rear deck lid accommodates the 4x6 inch full-range configuration consistently across all model years from 1973 through 1980, indicating a stable mounting cavity without dimensional changes across the production span.
Because full-range drivers include a tweeter element or high-frequency cone alongside the main cone, placement in a rear deck lid allows treble frequencies to radiate upward and reflect off the rear glass toward forward cabin positions.