3 quick questions on differentials, + deep pan transmission

[BerniniCaCO3]

I bought a posi lok unit off craigslist the other day to install in my currently open rear.

(1) what is the pin that holds the spider gears together called? apparently/maybe has C clips holding it in? Is it the thing called a crosspin bolt, and if so, what would be the crosspin retaining bolt? The posi I bought, has the spider gears just floating...
(2) can I buy a replacement? ...finding one might be substantially easier once I know the answer to (1)
(3) The clutches in a posi unit: I have not yet taken it apart, but just looking at it, the steel ribs -I count three- are the backing plates, SO, whatever space in between the steel ribs can be assumed to be the friction/clutch material?
(3.1) Rebuild kits are pricey. How thick is the clutch material brand new (just like, say, brake pads start at 12mm), so I can judge how used up they are? If they're almost fresh, I won't spend another $60-$100 on a kit.

(4) Lots of folks are advising a deep sump pan for my AOD. Now, looks like the filter is itself the pickup tube, and goes directly to the pump. SO if I buy a deep sump pan --made originally for some of the 4x4 vehicles with the AOD, or, buy a pricey aftermarket aluminum version-- do I need to locate the appropriate filter that will reach to the bottom of it?

[turbo2256b]

You can use the 4x4 pan and the 4x4 filter. It adds about 2 qts. The aluminum pan uses the same 4x4 filter. It adds 3 qts.

[pantera77]

I used a summit +1qt finned aluminum pan on the wr-aod in the 87, and just used the filter that came with it. I wouldn't go anymore than that, as it sits pretty even with the exhaust. P72Ford went with a +3qt pan and it sits low.

[P72Ford]

The B&M cast aluminum pan I used hangs lower than the front crossmember, and my car is low to begin with. Things would probably get interesting if I were to wheel it Bo and Luke Duke style...

[turbo2256b]

looky. Creamy is lowered abot an inch or inch and a half. Havent had any issues so far