Seems like a rallye dash would come with a 150mph speedo and something else like clock, performance indicator or tach - I mean if it just comes with a 120 speedo and blankout plate why call it a rallye dash?
Because the 'rallye instrument panel' had been standard on many models with the 150 mph speedometer as an option.
Originally the performance gage was standard and the tach an option that could go in the panel or on the console.
Later the Performance Gage became optional too. Kindof like the folding back seat in the fastback became an option. Why? $$$
