Rear End swap
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Tuned
Joined: Jul 2011
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From: Sacramento, CA
Rear End swap
I guessing this is going to be one of those dumb questions as I've searched for an answer and can't seem to find one.
I have a 66 F250 with a 4.11 diff. I bought a 70 F250 donor truck with 3.73 diff that I'd like to swap into my truck.
Do I drop the whole back axle, diff, hubs, etc? Or am I suppose to open the diff and change the gears? Seems both options would be pretty easy.
This should bolt right up, right? Ford didn't change that axle until 73, right? 1970 still had a 10 groove spindle and not the 29 groove one?
Bonus question, what is the "3rd member" I was reading about in some of the threads on the diff swap?
Joel
I have a 66 F250 with a 4.11 diff. I bought a 70 F250 donor truck with 3.73 diff that I'd like to swap into my truck.
Do I drop the whole back axle, diff, hubs, etc? Or am I suppose to open the diff and change the gears? Seems both options would be pretty easy.
This should bolt right up, right? Ford didn't change that axle until 73, right? 1970 still had a 10 groove spindle and not the 29 groove one?
Bonus question, what is the "3rd member" I was reading about in some of the threads on the diff swap?
Joel
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
Likes: 785
From: Simi Valley, CA
I guessing this is going to be one of those dumb questions as I've searched for an answer and can't seem to find one.
I have a 66 F250 with a 4.11
4.10 diff. I bought a 70 F250 donor truck with 3.73 diff that I'd like to swap into my truck.
Do I drop the whole back axle, diff, hubs, etc? Or am I suppose to open the diff and change the gears? Seems both options would be pretty easy.
This should bolt right up, right? Ford didn't change that axle until 73, right? 1970 has 29 spline pinion gear.
I have a 66 F250 with a 4.11
4.10 diff. I bought a 70 F250 donor truck with 3.73 diff that I'd like to swap into my truck.Do I drop the whole back axle, diff, hubs, etc? Or am I suppose to open the diff and change the gears? Seems both options would be pretty easy.
This should bolt right up, right? Ford didn't change that axle until 73, right? 1970 has 29 spline pinion gear.
1967/72: All Dana 60 gear sets have 29 splines, 3.73 introduced in 1967.
Companion flange (4851) specific to 10 or 29 splines.
Thread Starter
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Tuned
Joined: Jul 2011
Posts: 350
Likes: 3
From: Sacramento, CA
Ok. Good to know. Leads me to a couple other questions. Like if my truck has 10 spindles and the donor truck had 29, what do I do to make that work? Also, where are these "spindles" so I can count them?
Elder User
Joined: May 2010
Posts: 957
Likes: 3
From: Valley Center, CA
Hey again HillBilly,
I did the same swap, although my original was a 4:56
I would just swap the whole smash...the Dana 60 has some tough adjustments I'm told...might want to rebuild the
drums though and redo the seals. As far as the spline issue, my old diff was the low spline count, and the new one
was a 29, so I just got a sealed conversion u-joint...easy. And they aren't "spindles", they are "splines" we are
referring to-simply count the number of splines on the differential yoke...if you need more than two hands to count
them, it's a 29 spline.
(Just kidding ya Mate!)
Best,
Jason
I did the same swap, although my original was a 4:56
I would just swap the whole smash...the Dana 60 has some tough adjustments I'm told...might want to rebuild the
drums though and redo the seals. As far as the spline issue, my old diff was the low spline count, and the new one
was a 29, so I just got a sealed conversion u-joint...easy. And they aren't "spindles", they are "splines" we are
referring to-simply count the number of splines on the differential yoke...if you need more than two hands to count
them, it's a 29 spline.
(Just kidding ya Mate!)Best,
Jason
Thread Starter
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Tuned
Joined: Jul 2011
Posts: 350
Likes: 3
From: Sacramento, CA
Hey Jason. Thanks for clearing that up. Spindles v Splines.
Anyway, I just called all of the vintage places around and a few Diff shops asking for a "Conversion U-Joint" and nobody had any idea what I was talkin about. I tried to explain what I was doing and was told that I would need any sort of conversion kit for that. Saying that I should just use half of the drive shaft from each truck.
Can you tell me where you got your "Sealed Conversion U-Joint" and/or why the idea of using half the drive shaft wouldn't work.
I know this is a conversion that lots of guys do, I think I'm just making it a lot harder than it needs to be.
Joel
Anyway, I just called all of the vintage places around and a few Diff shops asking for a "Conversion U-Joint" and nobody had any idea what I was talkin about. I tried to explain what I was doing and was told that I would need any sort of conversion kit for that. Saying that I should just use half of the drive shaft from each truck.
Can you tell me where you got your "Sealed Conversion U-Joint" and/or why the idea of using half the drive shaft wouldn't work.
I know this is a conversion that lots of guys do, I think I'm just making it a lot harder than it needs to be.
Joel
Fleet Owner
Joined: Jun 1999
Posts: 24,552
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From: Creedmoor, North Carolina
John
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Tuned
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Thanks John
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Ford Parts Specialist
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From: Simi Valley, CA
Originally Posted by HillBillyBuddha
Anyway, I just called all of the vintage places around and a few Diff shops asking for a "Conversion U-Joint" and nobody had any idea what I was talkin about. 
So, what else is new?
I tried to explain what I was doing and was told that I would need any sort of conversion kit for that. Saying that I should just use half of the drive shaft from each truck.
So, what else is new?
I tried to explain what I was doing and was told that I would need any sort of conversion kit for that. Saying that I should just use half of the drive shaft from each truck.
Like this puppy that all 1965/72 F100 8' Stylesides with a two piece driveshaft came with: Ford: C5TZ-4635-F / Spicer/Dana: 210392-X / U-joint ~ 2 cups are 1310's, two cups are 1330's.
Posting Guru
Joined: Oct 2007
Posts: 1,144
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From: Sedro-Woolley, WA
If you have two Dana 60 full floater axles set up for Ford 3/4 tons then they should be a direct bolt up. Swapping out the gears in a Dana anything is a long, complicated process for a novice machinist. The first one I did was pure torture since I had no clue what the proper steps were to take one apart leaving me with no base line.
If you have issues with the u joints not matching (I believe they should be 1350 size) then you need to get a crossover u joint. Our local Carquest has been great for having these in stock but it is staffed with local hotrodders, not your average computer jockeys. Also a driveline shop will be able to steer you in the right direction and will understand what you are trying to accomplish.
I have learned to ask the people who actually do the work rather than the kids who sell you some box with a part number on it.
If you have issues with the u joints not matching (I believe they should be 1350 size) then you need to get a crossover u joint. Our local Carquest has been great for having these in stock but it is staffed with local hotrodders, not your average computer jockeys. Also a driveline shop will be able to steer you in the right direction and will understand what you are trying to accomplish.
I have learned to ask the people who actually do the work rather than the kids who sell you some box with a part number on it.
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
Likes: 785
From: Simi Valley, CA
If you have two Dana 60 full floater axles set up for Ford 3/4 tons then they should be a direct bolt up. Swapping out the gears in a Dana anything is a long, complicated process for a novice machinist. The first one I did was pure torture since I had no clue what the proper steps were to take one apart leaving me with no base line.
If you have issues with the u joints not matching (I believe they should be 1350 size) then you need to get a crossover u joint. Our local Carquest has been great for having these in stock but it is staffed with local hotrodders, not your average computer jockeys. Also a driveline shop will be able to steer you in the right direction and will understand what you are trying to accomplish.
I have learned to ask the people who actually do the work rather than the kids who sell you some box with a part number on it.
If you have issues with the u joints not matching (I believe they should be 1350 size) then you need to get a crossover u joint. Our local Carquest has been great for having these in stock but it is staffed with local hotrodders, not your average computer jockeys. Also a driveline shop will be able to steer you in the right direction and will understand what you are trying to accomplish.
I have learned to ask the people who actually do the work rather than the kids who sell you some box with a part number on it.
I'm not a kid w/a box w/a part number, I'm a 69 yr old geezer w/35 yrs of Ford parts experience armed w/the 1964/72 Ford truck parts catalog.
Posting Guru
Joined: Oct 2007
Posts: 1,144
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From: Sedro-Woolley, WA
1968/72 F250 2WD. If Dana 60 rear axle is from a 240/300/360: 1310 (C3AZ-4635-J = 1963/78 Galaxie/LTD / If from a 390: 1330 (C4SZ-4635-A = Same as 1964/66 Thunderbird).
I'm not a kid w/a box w/a part number, I'm a 69 yr old geezer w/35 yrs of Ford parts experience armed w/the 1964/72 Ford truck parts catalog.
I'm not a kid w/a box w/a part number, I'm a 69 yr old geezer w/35 yrs of Ford parts experience armed w/the 1964/72 Ford truck parts catalog.
And for the record, I in no way lump you in with the pimply faced twenty year olds in the chain stores that don't know what they are selling exactly. They are who I was referring to.
You don't need to defend yourself with me as you have helped relieve me of my ignorance on more than one occasion.
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