Here's from 'mymopar.com':
"Gear ratios available on the 8-3/4" axle through the years include: 2.76, 2.93, 3.23, 3.31, 3.55, 3.73, 3.91, 4.10, 4.56, 4.89, 5.17, 5.57. On OEM gear sets, the ratio is usually stamped on the ring gear edge."
I took the car to the guy who set up the rear, after hearing the noise he said it was a cracked tooth.