Worthwhile axle swap?
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5th Wheeling
Joined: Mar 2013
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Worthwhile axle swap?
My 1965 F250 with 352 engine has a limited-slip axle with a 4:10 ratio.
I have a chance to get a standard axle (i.e. not a limited-slip) from a 1967 F250 with a 3:73 ratio.
Is this a straight forward swap into my '65 truck? My intention is to use this truck for long distance towing and I thought the 3:73 ratio would be better for that as far as gas mileage was concerned. I would keep the C6 auto trans already in the truck.
Thanks, Gene
I have a chance to get a standard axle (i.e. not a limited-slip) from a 1967 F250 with a 3:73 ratio.
Is this a straight forward swap into my '65 truck? My intention is to use this truck for long distance towing and I thought the 3:73 ratio would be better for that as far as gas mileage was concerned. I would keep the C6 auto trans already in the truck.
Thanks, Gene
Laughing Gas
Joined: Dec 2010
Posts: 1,091
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From: Tucson, Arizona
I think your axle ratio choice should depend on what you're towing (how much does it weigh?) and how fast you want to go. Ideally, you want to be in the max power rev range of your torque curve. It doesn't sound like you really need a limited slip differential. A 3.73 will certainly cut down some revs over a 4.10 while still pulling quite well. You might even get away with 3.50s. Are you sure your automatic is a C6? The Cruise-O-Matic that came with your 352 in 1965 was not a C6.
Last edited by SuperSabre; Jul 30, 2013 at 06:13 PM. Reason: Messed up.
Ford Parts Specialist
Joined: Nov 2006
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From: Simi Valley, CA
1966: This ratio is very hard to find thru 1972, difficult to find 1973/85. Many people want 3.54's, few find them.
1980: 3.07 & 3.23 gears were first offered in Dana 60's, lotsa luck finding either!
And, if the rear axle ID tag is missing (as usual), how would one know what the ratio is?
AXLE code stamped on the Warranty Plate, but a parts catalog is required to decode it.
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5th Wheeling
Joined: Mar 2013
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Re: worthwhile axle swap
Bill: I know the junkyard truck with the 3:73 runs and drives so I think the axle should be ok.
Supersabre: my 65 F250 should have a cruise-o-matic, but somewhere along the line it was replaced with a C6.
I would be towing a small lightweight antique car to shows (car weighs no more than 3,500 lbs. Say 3,000 lbs for a trailer (haven't bought that yet) for a total of 6,500 lbs or so. So I need the truck to tow, lets say 7,000 lbs long distances, to include some steep hills (eg. Vermont)
So far, it sounds like the switch over (if it would work) is not worth the effort to gain approx. 2 miles per gallon in gas savings.
The junkyard truck with the 3:73 is readily available and I'm pulling other stuff off it--just thought the axle would be worth while too.
Gene
Supersabre: my 65 F250 should have a cruise-o-matic, but somewhere along the line it was replaced with a C6.
I would be towing a small lightweight antique car to shows (car weighs no more than 3,500 lbs. Say 3,000 lbs for a trailer (haven't bought that yet) for a total of 6,500 lbs or so. So I need the truck to tow, lets say 7,000 lbs long distances, to include some steep hills (eg. Vermont)
So far, it sounds like the switch over (if it would work) is not worth the effort to gain approx. 2 miles per gallon in gas savings.
The junkyard truck with the 3:73 is readily available and I'm pulling other stuff off it--just thought the axle would be worth while too.
Gene
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Cargo Master
Joined: Apr 2003
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2 mpg is significant in these trucks. If you get what seems to be an average of 10-12 now, 2mpg is a 16-20% improvement. You can't know for certain if the swap will improve mileage until yo do it. If it does, it should be pretty cheap and pay off quickly.
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OP has a 1965 F250 w/a Dana 60. What was the first year that 3.54 gears were available?
1966: This ratio is very hard to find thru 1972, difficult to find 1973/85. Many people want 3.54's, few find them.
1980: 3.07 & 3.23 gears were first offered in Dana 60's, lotsa luck finding either!
And, if the rear axle ID tag is missing (as usual), how would one know what the ratio is?
AXLE code stamped on the Warranty Plate, but a parts catalog is required to decode it.
1966: This ratio is very hard to find thru 1972, difficult to find 1973/85. Many people want 3.54's, few find them.
1980: 3.07 & 3.23 gears were first offered in Dana 60's, lotsa luck finding either!
And, if the rear axle ID tag is missing (as usual), how would one know what the ratio is?
AXLE code stamped on the Warranty Plate, but a parts catalog is required to decode it.
Fleet Owner
Joined: Jun 1999
Posts: 24,552
Likes: 74
From: Creedmoor, North Carolina
Bill: I know the junkyard truck with the 3:73 runs and drives so I think the axle should be ok.
Supersabre: my 65 F250 should have a cruise-o-matic, but somewhere along the line it was replaced with a C6.
I would be towing a small lightweight antique car to shows (car weighs no more than 3,500 lbs. Say 3,000 lbs for a trailer (haven't bought that yet) for a total of 6,500 lbs or so. So I need the truck to tow, lets say 7,000 lbs long distances, to include some steep hills (eg. Vermont)
So far, it sounds like the switch over (if it would work) is not worth the effort to gain approx. 2 miles per gallon in gas savings.
The junkyard truck with the 3:73 is readily available and I'm pulling other stuff off it--just thought the axle would be worth while too.
Gene
Supersabre: my 65 F250 should have a cruise-o-matic, but somewhere along the line it was replaced with a C6.
I would be towing a small lightweight antique car to shows (car weighs no more than 3,500 lbs. Say 3,000 lbs for a trailer (haven't bought that yet) for a total of 6,500 lbs or so. So I need the truck to tow, lets say 7,000 lbs long distances, to include some steep hills (eg. Vermont)
So far, it sounds like the switch over (if it would work) is not worth the effort to gain approx. 2 miles per gallon in gas savings.
The junkyard truck with the 3:73 is readily available and I'm pulling other stuff off it--just thought the axle would be worth while too.
Gene
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