Hi I have a 55 f 250 with a Dana 60 rear axle with the 4.88 gear ratios, I was wondering if I could replace the gears inside the pumpkin to a lower ratio to increase the speed of the truck at lower rpms

 

Yup. All it should take is a simple gear swap. searching Dana 60 (insert ratio desired here) will yield results. 3.54 is the lowest I've seen for Dana 60s though.

 

I am sure the more knowledgeable will chime in, but check on carrier compatibility. Some have different size carriers depending on gear ratio range (Thicker ring gears).

 

I started looking into this myself and Dana/Spicer in town says what they need is the numbers off the internals.With this the have interchange books to show a crossover of what fits our rear ends.On the later ones they use a stamped number on the housing.

 

Might be easier to just change the whole rear end. Mine also originally came with a 4.88 Dana 60 but when I got it had a Ford 9", so it was easy for my to just change to a replacement Dana 60 with 3.73 gears which are great for the highway.

 

Personally, I would swap in a different rearend with better gearing. I spent about 3 months back in 2009 looking for the correct gears to do a swap and ended up with carrier issues. Just my .02.