What axle do I have, and what ratio would be best?

[67dually]

Im buying a 67 f350 dually (352 4spd, non powersteering, drum brakes) off my grandfather with the goal of making it somewhat of a daily beater (add disc brakes and powersteering). I thought about doing a cummins/nv/getrag swap but the truck only has 28k on it and runs and sounds so good it would kill me to pull it... after taking it for a short ride this weekend I doubt the truck could do 65-70 which makes me think it has something like 4:88s or maybe even as low as 5's for a rear gear. So my question is what rearend do I have? dana 60/61 or the basic 70? and if I swap for a taller ratio what would be best? I completely forgot to look or write down the vin when I saw the truck

[gregamorton]

More than likely you have the first dana 70 with a oddball gear set in it. I went down that road one time and you cant get gears for it. Most of the trucks had 4.10s but I have seen a 4.56 gear rear end one time. In my one ton I am running a 1973 dana 60 with spacers for the dual tires with 3.73s. I believe that any of the dually rear ends from a ford up till the 90s but might work with just moving the spring perches to where they need to be. Depending on what you use your truck for you can find a 3.54 to 4.10 rear out of all big three manufactures.

[67dually]

More than likely you have the first dana 70 with a oddball gear set in it. I went down that road one time and you cant get gears for it. Most of the trucks had 4.10s but I have seen a 4.56 gear rear end one time. In my one ton I am running a 1973 dana 60 with spacers for the dual tires with 3.73s. I believe that any of the dually rear ends from a ford up till the 90s but might work with just moving the spring perches to where they need to be. Depending on what you use your truck for you can find a 3.54 to 4.10 rear out of all big three manufactures.

Thanks, Id definitely consider a newer 60 or 70 but Ive found a few name brand companies that have ring/pinion sets as low as 3:54 for the dana 70 (not HD or U or 2U just 70) and I would have the straight dana 70 correct?

[TNIceWolf]

My guess would be a Dana 70. At least thats what mine has. Mine calls for a 4:10 gear ratio. And yes.....65 or 70 mph and the engine is wound tight it sounds like.....but it really has more. Take a look near the top rear of the pumpkin....if its a 70 you will see it cast into the housing.

[averagef250]

Thanks, Id definitely consider a newer 60 or 70 but Ive found a few name brand companies that have ring/pinion sets as low as 3:54 for the dana 70 (not HD or U or 2U just 70) and I would have the straight dana 70 correct?

No, you do not have just a Dana 70. You have the old 23 spline boat anchor special Dana 70. It's a light duty Dana 70 (Dana 60 with bigger ring gear) with absolutely no options for gears because of the extreme pinion offset.

Keep in mind 28K miles in 1967 was 2/3 the average lifespan of an engine. Maybe it's in great shape, but 28K on 1970's oil and 4.56 gears at 4000 RPM is a different story than an F100 with 3.50 gears.

I drove a 68 F-250 4x4 home that had 38K original miles on it. It was pretty much junk from a hillbilly "restoration" , but the frame was in perfect shape and that's all I wanted. It was stuck in 4 lo with 4.56's. I got it running on a can of gas under the hood and drove it 15 miles home with my foot to the floor. The engine didn't seem to mind 4500+ RPM for that time. Figured it was a nice last hurrah for it before going to the shredder.

[67dually]

Thanks, Id definitely consider a newer 60 or 70 but Ive found a few name brand companies that have ring/pinion sets as low as 3:54 for the dana 70 (not HD or U or 2U just 70) and I would have the straight dana 70 correct?

No, you do not have just a Dana 70. You have the old 23 spline boat anchor special Dana 70. It's a light duty Dana 70 (Dana 60 with bigger ring gear) with absolutely no options for gears because of the extreme pinion offset.

Keep in mind 28K miles in 1967 was 2/3 the average lifespan of an engine. Maybe it's in great shape, but 28K on 1970's oil and 4.56 gears at 4000 RPM is a different story than an F100 with 3.50 gears.

I drove a 68 F-250 4x4 home that had 38K original miles on it. It was pretty much junk from a hillbilly "restoration" , but the frame was in perfect shape and that's all I wanted. It was stuck in 4 lo with 4.56's. I got it running on a can of gas under the hood and drove it 15 miles home with my foot to the floor. The engine didn't seem to mind 4500+ RPM for that time. Figured it was a nice last hurrah for it before going to the shredder.

Thanks, thats the response I was looking for picking up a cummins parts truck sounds like a better option... might just get an overhaul the way it sits