So I bought the early 99 F350 7.3l dually I was asking questions about a couple of weeks ago. I get the shutter in the rear differential on slow turns, so I'm off to change the fluid. I didn't get any owners manuals with the truck, so I have no idea what the capacity is. The VIN sticker says the axle is an "F2". I'm a bit torn about which route to take; should I do the standard gear oil then add the friction modifiers or should I just go the royal purple route? What are some other options? I don't want to spend a fortune on gear oil just to find out that I need to replace the clutch packs. The truck has 22K miles on it, but didn't move much in the last 5-6 years, so I suspect the clutch packs are fine.
Any thoughts and what is the capacity? Thanks for the help....
F2 — 4.10 limited slip, F-350 (dual rear wheels) and I'm thinking 2qt's of Ford synthetic 75w140 weight gear lube and 1- 4oz bottle friction modifier, or 2qt's + Royal Purple for limited slip, but you may want to call your local Ford Dealer for the recommended quantity. I used the Ford Lube myself but it's a personal choice.
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