3.89 gear ratio?

[sargentrs]

My rear end went out on me a couple years ago so I swapped it with one from a junkyard a buddy owns. My original was a 3.25. The one I got came out of '68 and the tag on it said it was a 3.89. After doing a little research on my VIN number, I don't see where 3.89 was a standard ratio. Did I misread the tag?

As a side note, I just swapped the pumpkins, didn't want to swap the whole rear ends. Yanked both chunks, swapped the new one to the old rear end and put it all back together. Then went to fill 'er up with 90W and....OH CRAP! My old rear end had the filler plug in the chunk. The '68 had the filler plug in the housing. I had no way to put in oil in it. So I drilled a hole high up on the housing and put a self tapping bolt in it.

[James72]

I don't know about the ratio, but I have run into the "no fill plug" situation in the past, an old schooler told me to fill a ziplock freezer bag (or two) with the needed amount of oil and stuff them in there and bolt it up. Diffs are tough and the bags were no match, I did it and ran 20,000k before I sold it. Id rather see a bag or two in there then a thread from a self tapping bolt.

[sargentrs]

NOW you tell me!

[Calvin Gunter]

I had the the no fill plug blues and just filled it through the axle tube.Before putting the second axle in let the axle tilt away from the tube and pour it in.

[sargentrs]

I don't feel near as stupid now. At least more of you guys have had the "no fill plug" issue.

On the original topic, I figured out where the 3.89 gear ratio comes from, thanks to the NPD catalog. Downloaded it yesterday and have been scanning it and found 3.89 gears were, apparently, on '61-'63 models. The rear end came from a '68 and NPD doesn't list that on them so maybe it wasn't the original rear end in the '68. Mystery solved!