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Rear axle change

jeffc

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Jul 14, 2021
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calgary,alberta
I'm looking at a 1966 Dodge D300. I didn't really want a 1 ton but the cab and box are super clean, rust free and it runs well. Is it possible to swap in a 3/4 ton rear axle with a taller gear set or any other options? I believe it has 4:56 gears right now. Thanks for any help.
 
You can stick in an 8 3/4 for that matter but will probably have to swap out the driveshaft since the rear will most likely be shorter in that aspect. Is the truck a dually? I had a 79D300 that was a single wheel with was was called a modified 60 in it. Not sure if that was just a 70 like what's in my 97 diesel....a 60 cover fits it.
 
It's not a dually. After some research, it looks like it may be a Dana 70 and taller gears are available. Thanks for the reply.
 
The casting on the diff center should have a casting mark on the driver's side towards the top at the axle tube end.
A 60 cover would not begin to fit the 70 in my 83 frame. I have never check the axle under the 76 dually van but it does look more like a 60 than a 70.
 
The casting on the diff center should have a casting mark on the driver's side towards the top at the axle tube end.
A 60 cover would not begin to fit the 70 in my 83 frame. I have never check the axle under the 76 dually van but it does look more like a 60 than a 70.
There are 3 (don't think there's more) different 70's and I know for a fact that the 60 cover fits the 70 'U' series Dana. Even the limited slip internal parts from the 60 fit the carrier. When I dug into my 70 I did some research and there are even some bearings that are the same although not all of them. I just happened to have a spare 60 cover and tried it and it was a perfect fit. Also, a 60 will have '60' cast into the right lower strengthening rib....but my 70 doesn't have anything in that area.
 
My 70 was stamped or cast one the driver's side center section. I don't think a 60 cover would begin to fit.
I am cleaned up for the day but if I remember to I will take a picture of the cover.
 
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