2.66 low gear vs close ratio

JoesEdge said
I've been following this thread because I've wondered what gear set I had in my transmission, and I had a couple of questions.

- If the trans is already in the car and driving, is there away to find out what gear ratios you have without pulling it out and opening it up?Yes

- Were there any A-body trans built '70 and later (newer) that had the 2.47 gear set? From the factory, what would have the intended of a vehicle that had a 2.47 gear set? AAR ROAD racing

I'm barely getting my Duster together but been driving it on the weekends. I haven't opened up the diff to verify my rear gear, but the tag says 3.21:1. Is there a question here?

So far, the transmission seems to shift good and the RPM's are right (i.e. pulls good in the appropriate gear even at a slow cruise). 1st gear isn't very short at all, and neither is 2nd gear. guess that's why I wonder what I have in there. I did have the transmission rebuilt, but forgot to ask what ratios I had. The car previously had a 3 speed (A230).

As to figuring the tranny ratios; Drive the car in 2nd gear up to exactly 40mph. Note the exact rpm. Shift into third and drive it back to 40 mph, and now note the new rpm.Stop the car. Take the smaller rpm and divide it by the larger. This will give you the 2-3 %split. Compare to the posts. .
Example: 40mph 2nd = 3063 rpm, and 40 in 3rd = 2233 Then 2233/3063 = 72.9%split. This would be a 2.66 box. The 2.47 box would be 75.7%. the od box would be 59.9%. The rpms will be different depending on the rear gears and which trans is involved. I just threw these rpms out there as an example. The % splits is what tells the story.
The AAR was a short lived series, maybe a couple of years, IDK
There are threads on how to figure out your rear gear.
Thx for dropping in.