I need to replace the Dana 44 in my 78 F250. I have 3.54 gear ratio both front and back according to the tags. I have found a set of Dana's that have 4.09 gears. What can i expect from the 4.09's are they going to be better for road driving, or are they better for off road?

Which is the better gear ratio?

I am clueless when it comes to gears and such.

 

It all depends on the rig. Is it stock? Is it lifted? What tire size are you running? Here is a chart to help you figure it all out.
The white is where you want to stay out of. The yellow will give you better mpg. The blue will get the most power to the ground. The green is the sweet spot, maximum mpg and power ratio. The numbers inside the chart are the RPM of your engine at 60mph. Now, these numbers are not exactly what you will turn. That number all depends on the rest of your drive train, like your tranny and the hp of your engine. All of these charts on the web are just the average, but will get you in the ball park.

 

Thanks.
I have a 400 with a C6. I can't read the tag on the transfer case so that is an unknown.