Rearend id in fender tag?

H22A4 said
Trucks were exempt from fuel economy standards that were coming in so that’s why they were still available with 3.91 gears!

That’s the loophole AMC used when they came out with the 4WD Eagle.

Yes I was just making a useless point that they still made a 8.25 3.91 after 72, just not available in cars?