4.8 to 5.3 questions..

[89chevy]

I have a 1999 ecsb 4x4 with 4.8 and 3.73 gears, I just got back from my first trip with this truck, it did great except for the long rolling hills on the interstate, It was really hard to maintain my 70-75 mph speeds without it downshifting on these hills which i dont like, it was really bad since i had my 700 pound motorcycle in the bed of the truck. My old 1989 silverado with 5.7 TBI never had to downshift going up hills on the interstate and i want to make my 1999 more like that. Would dropping in a 5.3 help much with this? Yes, i already know a 6.0 would but i already have access to a 5.3, so thats why im asking about it. I would like it to not have to work so hard on the next long trip on the interstate hills so was thinking of dropping the 5.3 in if it will actually do better with this...?

[Outlawz2004]

You have the lowest rated hp 4.8 that they made, only like 255hp. Just swapping to a newer 4.8 will make a difference, or swapping the parts on your current one to produce more hp such as cam and get some custom tuning done. Swapping to a newer 5.3 will make a big difference as well. There isnt much hp difference between a newer 5.3 and 4.8, but the extra torque it makes will help with the towing. Tuning alone will make a big difference by itself, along with the extra power, your shift points (as well as downshift points)will be adjusted for better drivability.

[Chriscon7]

What differential gears?

[Outlawz2004]

He posted 3.73s right there in the first sentence.

[Chriscon7]

He posted 3.73s right there in the first sentence.

Dammit. My bad.

[jrmchevyman]

The 6.0 would be better like you know, but the current 4.8l you already have would be okay if you had a little work done to it like already stated. A new cam, custom tune and LT headers would wake it up.