the BLACK 4-speed carpet dilemma stems from the "concept" of the '68 Road Runner & '69 340 Swinger (bench seat cars that had a 4-speed STANDARD)

the cars they were based on had STANDARD rubber floor mats & there was NO rubber floor mat for a 4-speed hump - so, 4-speed cars received BLACK carpet.

by the time the '68 Road Runner reached production carpet was STANDARD for all.

the '69 340 Swinger 4-speed had carpet, with an automatic carpet was OPTIONAL $$ (for '70 the a-body got 4-speed rubber floor mats)

I've seen a number of original '68-'70 Road Runners & Super Bees with colored interiors (bench & bucket) with 4-speeds & BLACK carpet

I've never seen an original Charger R/T, Coronet R/T or GTX with colored interior, 4-speed and black carpet (do they exist?)

I've never seen an original console equipped colored interior 1968-'70 B-body w/4-speed and black carpet