Tim,
I guess the code you are looking for would be the numbers Wurlitzer46 found 39-10 for the 3.90 and 40-11 ? for the 4.11.
I Haven't taken a rearend apart in years, I always remember the numbers being stamped on the rear face of the pinion gear as being the ratio.
If Chevy had a different number stamped for a stock code I'm not familiar with that. All of the aftermarket gear companies had them stamped on the rear face of the pinion gear.
I wasn't trying to be a smart--- with the "simple math"thing.
maybe it came across wrong, sorry if it offended you, didn't mean it that way.
