I recently replaced my stock 2.73 ratio open rear with a 3.73 posi unit in my 72 Chevelle SS and having a little trouble figuring out how fast I'm going on the clock. The car also has 245/60r15 tires on stock 5-spoke SS rims and the original TH350 auto. I know this ratio was available originally in the car and was wondering if anybody had any info on the different speedo gears that were used in the trans. I also know that there are different color gears for different ratios, so looking for one that will set me speedo right, but don't know what the color may be. if anybody has any info it would greatly be appreciated, Thanks