Rear axle paint markings

I found this paint marking on my AAR Cuda's rear axle. I know its for the gear ratio but don't know what gear ratio.
Looks like 078 to me. What do you think an does anyone know what ratio it stands for.

078 # for a 3:91 SG
076 # for a 3:55 SG
The only two ratios for TA / AAR 8-3/4

What about this one, A date code maybe 4 - 8 Z or 4 - 8 7

Clean the pumpkin rather carefully - some of them have all kinds of info on them.

Here is the date code

Mine looks like 4 - 8 Z date code for a SPD 414 TA Date Code

What is the significance of the Letter in the code?
X, V, Z, etc