To answer your question first:
Gear oil -
Front Diff: http://shop.advanceautoparts.com/web...T|GRP2035_____
Rear Diff: http://shop.advanceautoparts.com/web...T|GRP2035_____
^^^^ Synthetic PLUS already has additive for LSD if your truck is equipped
Trans fluid: I stuck with the Mercron LV - It was under $6/qt from the dealer. I'm sure there are substitutes, but I didn't want to bother.
I bought my '05 F350 back in April with 136,000 on it. Seems to be well cared for but I wanted to establish a maintenance baseline with EVERYTHING. So I did just that.
Oil Change w/ Motorcraft 2016 filter
Fuel Filter (both filters)
New Coolant Filter (truck already had system installed)
Both trans filters and fluid (Motorcraft Filters are avail at Oreillys MUCH cheaper than Ford)
Transfer Case (2 1/3qt of Royal Purple MAX ATF)
I've been running Motorcraft Cetane booster religiously
New Air Filter
I bit the bullet and did the Restore/VC-9 coolant flush and switched to Zerex ELC (ZXED-1). Truck is running at 180-184* on 80* day. Changed the coolant filter again when I did the switch.
I've done all the work myself and it did cost a little bit to do it all basically at the same time. BUT -This is a truck I plan on keeping for a long time, so spending a little now so that I KNOW how many miles are on each fluid/filter is good peace of mind. ~$600 isn't that bad when you consider that peace of mind.
I've still gotta do my diffs as soon as I've got a spare $100.
One bit of advice - If you have an Advance Auto Parts near you. You can buy things like the air/fuel filters (and oil filters) ONLINE and pickup at your store. There are a ton of coupon codes listed on their site; I use them ALL the time for stuff! My air filter (factory Motorcraft) lists for $66.96 - I used coupon code "BIG25" (spend over $60, take $25 off) so my filter cost me only $41.96! Do a google search for more - Sometimes you have to be creative in how you buy things (quantity wise - separate orders to use multiple codes), but I've saved a ton doing it this way.
Hope that helps.