My Silverado 1/2 ton,350 with 2:73 rearend,doesn't have the power to pull a 5000 lb trailer.It starts to over heat on hills,has no power and a head wind is a problem too.
I've always pulled in drive.The radiator is clean.
I'd like to change the the rearend gears to a 3:73 or 4:10 ratio.
Looking for some input on which would be better.I'm leaning towards the 4:10........?

I would go with the 3.73 if you're only pulling 5000 pounds. Going to the 4.10 will really hurt in fuel use department. If you're over 5000 pounds of trailer, you should look at your Combined gross weight rating.