I recall at the time that factory tachs were notoriously inaccurate - and I've proved it myself.
Most guys just added an aftermarket tach, which could also be placed in a more visible location for when things got serious.
I've never seen the B-body OEM tach called out on the FT.
My blue Hemi RR coupe came w/o a tach - no radio or other options, either; just whatever it took to order a Hemi 4-speed car.
Original owner was a USAF airman who raced the car & added gauges.
The black coupe had a radio, but no tach or other options, and was also raced.