What part numbers did you search for? I find it hard to believe these gaskets are not available, having recently purchased them myself.

I'd want to use a gasket even if Inhad to make them from the correct thickness gasket paper. The gasket thickness for the center section affects where the side gears are and how the axle shafts slide in. If too far off location the axle shafts will flex sideways and fret on the splines in the side gears. Not sure how serious a concern it is but if using stock gasket you don't have to worry much.

Here's some info from the post describing my rear gear swap.

Originally Posted by Grigg
Here's a Tech Tip.
http://www.stovebolt.com/techtips/axles/1%20Ton%20Upgrade/

Gaskets,
Pumpkin gasket; thin, and cover gasket; thick. PICTURE Ferl-Pro part numbers RDS 5090 and RDS 5988
I like to use Permatex #2 on most gaskets. Put a little on and spread it about as thin as possible with my finger, flip the gasket and repeat. Don't worry about loosing any when flipping, plenty enough stays on the gasket.
PICTURE
Also use the same Permatex on the bolt threads to seal them.
PICTURE
If I spread just the right amount on the gasket only the tiniest little bit squeezes out.
PICTURE
Also washed and removed any burs from axle and hub and put a new gasket on, Fel-Pro 55350. I didn't use any Permatex on the metal flange gasket because I'm not sure if it is a good idea? Time will tell if I should have. Did use Permatex on the axle flange bolt threads.
PICTURE

•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-