I have had several trucks over the years.
stock 4.10's with 33's, 31's
4.88's with 33's -35's
Currently dual t/c with 5.29's and 35's

Even with 5.71's and 35's no way you would only be going 25 in 5th gear in high range.

Plug your numbers into a gear calculator like this
https://www.marlincrawler.com/java/getspd_calc.html

 

Yeah something's not right, sounds like something wasn't put back together just right. Gears are a tricky skill to master because everything has to sit just perfect for it all to work in sync. 1/100 of an inch off and you could start having the gears teeth start to get all chewed up. I have 5.29's with 35's and I can run 60mph with no problem. Even though it says you are in 2wd are you sure your not stuck in low range? If you put it in low range does it rev even higher?

 

Yup, 4.88 on 35's here. Something funny going on here. How did you get the new ring gear back on?