1965 c10 ratio gears...swap..fitting help!!!

[Vincentnova]

Hello
I feel like i cant find any precise information about it
I have a 1965 c10 4speed low gears
Never use the fisrt gear
All original
And like most know on highway....60 mph engine screaming loool
Im pretty sure i have 4.11 at the rear end..
Well i dont want swap rear end
And dont want swap tranny either

What kind of rear end are those ?
Where can i find gears ?
Im between 3.42 and 3.08
Can i find a set of gears that could feet the actual diferential ?
If no please let me know what to use and where to look
Thanks