Trans fluid in 79 Rear diff?

[willywoo28]

As the title states I discovered that the P.O. put straight atf in the rear diff. I just pulled the plug on the side of the diff case and found that the fluid is very thin, clear (red), and smells like roses compared to gear oil and additives that i have used on other trucks.....

Couple questions:

1) Is this okay to keep running since it is clear and no Rear end noise?
2) How Long? (my guess is that it has 65k miles from the P.O.'s engine swap).


There are no metal shavings, nor any discoloration of the fluid. It is my daily driver, so I am just curious.

Any input is always appreciated.

Thanks!