It may be a slight enough difference to not matter much, I agree.

I like to do things right to the best of my ability/knowledge. I also believe in providing sound advice. Thus the recommendation to use the original thickness gasket and the reason why it might matter.
Then whoever chooses can follow it or not and base that decision on a sound understanding of the situation.

When you don't understand all the factors involved and make "judgement calls" the results aren't always pleasing.
Or better to know when you're cutting corners than be surprised when it didn't work out.


PS
To add to the gasket thickness discussion (without having them to measure) I suspect the differential cover gasket is 1/16" thick, and the carrier gasket 1/64 or 1/32"; same shape and same bolt pattern. If gasket thickness didn't matter why didn't GM only offer one thickness gasket, less trouble and expense to make and stock one instead of two?

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
---All pictures---
"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-