Well your bound to do this after hearing most of the detail against it, so here is the last bit you might want to know.
With stock 3.55 rear gear in over drive, the final ratio is 3.55 x .70 = 2.49 rounded off.
With 4.56 x .7 = 3.19 rounded off.
There is only .70 difference between the two ratios in over drive.
In all other gears the difference is
First gear stock = 2.84 x 3.55 = 10.03 vs 2.85 x 4.56 = 12.95.
Second gear stock= 1.55 x 3.55 = 5.50 vs 1.55 x 4.56 = 7.07.
High gear is 1 x 3.55 or 3.55 vs 1 x 4.56 or 4.56.
OD is .7 x the final ratio as above.
You will have to rev the motor to 3500 rpm to get its max torque in any gear ratio.
.
This torque us mechanically multiplied by the final gear ratios in each gear.
Engine torque is what moves the weight. Changing gears does not generate more horse power
If the final torque total is less than the motor can pull 'reasonably', the trans is in danger of ballooning the converter as it will be out of lockup most all the time when towing the total load plus the tremendous heat generated over the pull time.
There are very few that get this level of analysis to show the likely real time conditions for your application.
Good luck.

 

It pulls fine on level ground now. Periodically I may have to pull hill. I don’t do much too much long-distance travel. Without changing tire size I figured the gear ratio change would help on hills

 

I was thinking it would be like granny year except for higher. It doesn’t matter what size engine you have a four-cylinder can pull a trailer uphill if it’s geared right. Am I right or am I wrong?

 

Please help me understand from Randy’s ring and pinion www.ringpinion.com To me it appears I would be within the perimeters to benefit from this mod. If you saw this low mileage second owner maintained truck you would see why I am hanging on to it.

 

Hope it works out for you but you are pushing the limits of your truck. One other point that I have found out is that the brakes really are substandard on our vintage trucks. Oh, another thing is that the rear diff is an 8.8" rear while the 5.4L trucks came with a 9.75.

 

Yes. To be safe, disconnect the front driveshaft if you do this.

 

No worries on the brakes the trailer has its own breaks you don’t even know it’s back there when stopping at help stop the truck by itself. The weight distribution bar makes it to where there is no weight on the tongue either so there’s no bouncing. Just doesn’t pull Hills very well it pulls them. just very slow

 

Everything we tell him based on fact, is dismissed.
Why come and ask in the first place?
Good luck.

 

 

Good thing you did go with 4.56 in both axles. The 4.6 has relatively low torque for a truck engine and needs to be wound up to move out.

Thanks for reporting back! Glad you are happy!

 

Glad you are going 80 mph presumably towing a 30' TT??

I don't think anyone 'helped' you with this decision, but if you are happy with it, that's all that can be said..

Changing your rear gears DOES help multiply the amount of torque getting to the ground at the wheels, so what you are seeing in better towing performance is expected..

All I can say is good luck and happy camping..

Mitch

 

Glad you are happy with the result! Stay safe out there!

 

 

I went from 3.55 to 4.10 in my truck. Best thing I did to it.