61 Rear End Advise Please

[blown240]

I noticed that the rear end of my 61 Panel started whining on the freeway. I checked the fluid, it was low, so I filled it up. Over the next couple days it leaked out. At lease as much that will leak out the pinion.

Should I just go thru the rear end I have, or swap in another?

I would really like to get rid of the 4:11 gears if I swap out the diff, but I for sure want to keep it 6 lug.

A 63-70 12 bolt may be my best bet, but not sure on the gear ratios. a 3:73 or 3.90 would give me a nice freeway gear. (350/700r4, 235/75/15 tires)

Money is a big concern, so I need best bang for the buck...

So do I repair the Eaton, or swap a 12 bolt?