Which Tac Is Correct For A 70 RR With Rally Dash

[soundhd]

Replacing a Rally Clock With a Tic Toc Tac in a 70 RR question

Recently purchased a 70 RR with a rally dash, been dealing with what I originally thought was a defective tac but just realized it is not a tic toc tac but a Rally Clock.......Is replacing the Rally clock with a Tic Tic Tac just simple swap out? What was the whole idea behind a Rally Clock anyway?

 

[6pktgo]

Factory Tic Toc Tac

This is a untouched factory 70 B Body rally dash tach. Sorry about the poor quality but you can see the needle behind the clock & the red line starts at 5,000 on this one.