It takes a 14MM Allen head wrench, I got it from AutoZone, $7.50 for 3 different sizes (12,14 & 16). I filled with Mobil 1 W75-90 synthetic (top of fill plug). It takes 1.1 quarts per the manual. I had to use cheater bar to remove & tighten plugs. I used Locktite on threads..Posted just for info...

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2000 Ford 7.3 Powerstroke 4x4
2006 Mazda Tribute
1983 Black 300 D (donated to charity)
1993 Teal 300 D (160K) Sold
"I love the smell of burnt diesel fuel in the morning, it smells like ....VICTORY"

Semper Fidelis
USMC 1973-1976

IS GEAR OIL SAE 140 ACCEPTABLE, if SAE 90 's not avail ?

W140 is too high for a rear end, use a W75-90. Most manuals use W90. I decided to go Mobile 1 synthetic in all my vehicles.

__________________
2000 Ford 7.3 Powerstroke 4x4
2006 Mazda Tribute
1983 Black 300 D (donated to charity)
1993 Teal 300 D (160K) Sold
"I love the smell of burnt diesel fuel in the morning, it smells like ....VICTORY"

Semper Fidelis
USMC 1973-1976

Do I have to replace 140 with 90 immediately or it can be used till next service?

It's just replaced last week.

Unless you drive short trips, I would change it. The thickness of the heavy oil (W140) might heat up the rear end on long trips..

__________________
2000 Ford 7.3 Powerstroke 4x4
2006 Mazda Tribute
1983 Black 300 D (donated to charity)
1993 Teal 300 D (160K) Sold
"I love the smell of burnt diesel fuel in the morning, it smells like ....VICTORY"

Semper Fidelis
USMC 1973-1976

Thanks