Ford E-350 Thor Vegas Rear differential Type?

But still, why do you need "spare" oil?

It doesn't consume any gear oil at all. The only way you'd lose some is through very leaky seals (which would take your brakes before it got too low) or physical damage to the cover, in which case you'd probably need a tow anyways.

I can't get under it to look for a tag.

jolooote wrote:
Hmmm...My manual lists Dana M70FF (M267FF), if Limited Slip, Synthetic, its 75W-90. If its M70FF Conventional, its 80W-90. How do I kno which? It lists 75W-140 only for the M60.

75W-140 will protect across the greatest temperature range. That's why its required for the Dana 60.... it's run right up to its limits in the vans (which have a GCWR up to 20,000 pounds with the Dana 60). It's a good oil for your Dana 70 too.

I also have a Dana 70, limited slip. I've been running 75w140 pretty much since I bought it at jut over 100k and I have almost 410,000 miles now, 50% of that is towing and my typical weight is 22,000 pounds combined.

Don't put conventional in there. If you read the fine print, you have to then change the gear oil at every oil change.

Most Dana differentials have a tag listing the gear ratio and oil requirement.

Richard

Most differentials have a tag listing the gear ratio and oil requirement.

Richard

Hmmm...My manual lists Dana M70FF (M267FF), if Limited Slip, Synthetic, its 75W-90. If its M70FF Conventional, its 80W-90. How do I kno which? It lists 75W-140 only for the M60.

Why do you feel like you need "spare" gear oil?

It is a Dana 70, you may or may not have Limited Slip (probably not).

It takes 75w140 full synthetic, and is rated for life (or every 150,000 miles for Ambulance use).