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Transmissions and Rear Ends Three on the tree or four in the floor? Shift it all here.

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  #1  
Old June 7th, 2020, 06:22 PM
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jmfurgason jmfurgason is offline
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Default Tranny And Diff

How often should gear oil be changed on sm420 and 44 Dana . Just a Sunday driver ? Thanks be well be safe . JF
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  #2  
Old June 9th, 2020, 12:26 AM
James James is offline
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Default Re: Tranny And Diff

SM420 or the Dana 44 - Maintenance Manual says check every 1,000 miles, drain and refill every 10,000 miles.
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Old June 9th, 2020, 03:39 AM
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Default Re: Tranny And Diff

Thanks James appreciate the response. JF
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Old June 9th, 2020, 06:00 AM
GMC_Dude GMC_Dude is offline
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Default Re: Tranny And Diff

Remember that lubricants are vastly superior today as they were when those specs were written.

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  #5  
Old June 9th, 2020, 06:05 PM
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Default Re: Tranny And Diff

Hey Dude , soooo what would you recommend ?? Thanks to all JF
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  #6  
Old June 9th, 2020, 10:22 PM
tbucketnut tbucketnut is offline
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Default Re: Tranny And Diff

For casual drivers, I replace gear oil every other year.
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1953 Chevrolet 3100
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Restoration is now started, still looking for an oldsmobile style power steering pump
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Old June 10th, 2020, 03:21 AM
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Default Re: Tranny And Diff

I am using Valvoline 80w90 not conventional, every other year good?? JF thanks tbucketnut
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Old June 10th, 2020, 03:22 AM
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Default Re: Tranny And Diff

meant not synthetic CORRECTION JF
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  #9  
Old June 16th, 2020, 05:24 AM
thenonoman thenonoman is offline
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Default Re: Tranny And Diff

I just replaced what seems to be the original oil in the diff on my 65. I suggest a little more often than that. It was sludge-tastic. I expect to find the same in the trans.
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Old December 7th, 2021, 06:07 PM
Jim A Jim A is offline
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Default Re: Tranny And Diff

Since I found several places with very different capacities for the Muncie SM420 on my 1960 1500, I figured I would add one more.
Started with old oil just below fill hole and drained about 3/4 of a gallon jug .
I filled to the drain/fill hole through the shifter neck (since it was already off and much easier) with exactly 3 quarts.
At the current price of $10/ quart, it is nice not to buy extra.
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