I recently installed a true trac and it feels like lost a lil topend with my 342s I am running a 265 60 17 tire. Would 4.10s help out my topend? Thanks

 

A posi change won't impact anything power wise. Depending on what rpm you want to turn on the freeway, 4.10's will always feel better than 3.42 in a N/A 4.8L

 

I was told but for some reason it feels sluggish going to third gear

 

i like my 3.73 with a 263/65-17 tire. keeps me about 2000rpms at 70mph. i do however have a 5.3l

for you with a 4l60e
all are at 70mph

3.42 1908rpms
3.73 2081rpms
3.90 2137rpms
4.10 2288rpms

if you do any highway i would say 4.10 would be a tad much but it would be fun to drive tho. im kinda liking the 3.90 or 3.73. the 3.73 might be easy to find some used ones for cheap but the jump isn't that big.

 

What are your mods?

when the truck shifts into 3rd you are pushing a brick thru the air at 90mph+

 

Longtube headers, cai and 3 in pro xs dumped no cats also a slp underdrive pulley with a true trac. Tuned by spike speed and performance

 

3rd gear is not considered "the top end". Do you mean its just sluggish in third gear or high in the RPM range?

If you want more power higher in the RPM band, a cam is the answer. You will like 4.10's better than 3.42's regardless. You will go through the gears much faster and it will go faster in the 1/4 every time.

 

It used to pull a little harder in third before I did a truc trac, I race a 03 gt I got him by truck length then I put on my true trac and I was half a truck in front of him his mods are 4.10 gears 5spd and cai and plenum also a hand held tuned

 

Sluggish in third gear

 

Put 4.56 in it if you don't drive on the freeway a lot. It will feels a ton better.