I lost the rear end in my '90 w350 auto, 3.07 gears. Replacements are not available unless you can find used. The case and carrier is specific to this ratio. That means I will probably have to replace the whole unit and re-gear the 60 up front. I have a lead on what I think is a 3.73 replacement.

What do you guys see while towing/ hauling out of over-drive with 4.10' and 3.54's, as far as mileage, comfortable cruising speeds, etc?

Also, I have seen a rear, mod 60 from a Ford F250 with 3.07's.
My understanding so far is that 3.07 is not available at all in a 70 anymore. Does anybody know if Ford used a ratio close to the 3.07 in a 70? I can get an axle built with warranty for what most salvage yards are asking for used. I don't have OD, and would like to be able to see speeds greater than 50mph.

Thanks guys, Don

 

I can't help you about the Dana 70 part,...

but from experience using a gasser 460 and non OD transmission, without OD and a low rpm engine like the CTD I'd use nothing lower than its current 3.07's if you spend any time on the superslab. Not considering transmission slip, with 3.73's you'd be doing good to hit 70 at around 2800 rpm. With 4.10's you'd be be about 6-7 mph slower yet at the same rpm.

Have you tried a search for another rear end? There's got to be some of them available (I clearly remember the hassle of finding a B100 Dodge van front rotor once... 20 years ago!). Even if it is tough, its got to be easier than doing gear swaps fore and aft.

 

I have 2 93s with 3.54s, the 2wd has some mods to the pump, gov etc. personally I wont push it beyond 65mph without O/Dand thats tops. 55 to 62 feels good and pulls great there. I have made a few runs hauling 7-8k at 55 60 mph no O/D and got 14 mpg or so. The 4x4 will cruise 55-60 comfortably there and get 14 empty. Personally I think If its not a daily driver for you, with a lot of highspeed driving it will be pretty nice and not a problem. Also the run with 8k saw OD some, but the trans temp started to climb a bit so we slowed down and locked out. Them horses dont like 80mph anyhow.

 

Thanks guys, I would like to make it a rpimary driver, and will look for 3.07's for a bit longer.

 

Wish I could convince one of my coworkers to sell me his 89 CTD, Id give you the diff, I just want the interior and motor etc. Its become the rolling rust bucket.