Not Another Rebuild Thread....

[McMurphy]

Ok...
So yesterday I took my read diff cover off again and shot these pics of the gear ratio.
So far so good eh?
Then I took off the gasket that was on there, and started working out that curl you get on the bottom of your pumpkin cover from.... Ohhhh lets say, jacking the rig up by the rear diff..... And though I was super careful taking the gasket off, chances are it is the original and since I have it off I may as well change it.
With old gasket in hand, and a small shopping list, off to the local parts store I go. Then I stand at the counter for 45 minutes while the old guy tries to look it up on the computer...then in the books...then takes the gasket in the back and tries an open-the-box comparison... only to return and tell me they dont have it.
I would not be so frustrated with this, if it wasnt for the stupid (or at least seemingly stupid to me) questions involved.
Me: I need a 12bolt posi rear diff cover gasket for a 66 C10 half ton, and the gear oil for that please.
Steven Hawkings of Auto Parts: What size engine is that?
Me: ???? in line-6 250 or 292
Him: Power Steering?
Me: WTF ????

Could anyone explain to me what difference anything forward of the drive shaft has to do with the rear diff gasket?
Please?