[CdnoilRAM]

I used the royal purple gear oil when I did mine this summer. I'm not sure where you are located but I get mine from mopac in calgary, there's also one in edmonton. You can also order amsoil, it's probably the best, but you can also walk into can tire and pick up the shell rotella great oil and it's a good one in a pinch.

 

[CdnoilRAM]

Honestly, yes. Unless you've cooked your fluids there should be no reason to change them out until 100-130,000kms. I'd swap tranny fluid at 60k and do new plugs, but not much else would really need to be done. Gear oil is extreme duty oil by nature, so it can go a long time before needing to be replaced. Now, there's nothing that says you don't have to swap the fluid for better stuff like a quality synthetic, but it's not a must. If it's a new-to-you truck, then it might not be a bad idea, just so you can open up the cases and see what kind of wear you have going on in them.

 

[CdnoilRAM]

depends on which oil you go for. The Amsoil and RP are similarly priced, and any of the other conventional or semi-syn will be much cheaper. No gaskets to replace, just pick up some liquid gasket from the parts store and that's all you really need since the transfer case should have a drain plug on it. Be sure you know if you have a LSD/tru-trac, if yes, then you'll need to add some slip additive to the rear.

Here's some info from the amsoil site that has quantities needed and oil weights:
http://www.amsoil.com/mygarage/ProductRecommendations.aspx?FromIndex=1&url2=2007+DODGE TRUCKS+RAM 1500 PICKUP+2