What gears should I use in my rear end?

[Kerlijah]

So I'm saving up my nickels and dimes, hoping to get different gearing soon. Unfortunately, when it comes to gearing, I dont know jack
I drive my truck every day, mostly just in town, but I also drive it a lot on the highway. I dont have a tach, so I cant say exactly how many rpm's I'm turnin at 65 down the highway,(way high though I'm sure) but I can tell you Ol Yeller really doesnt like goin that fast at all, it's practically screamin!!

So my question is, what would yall recommend for gearing in my truck? It's 2-wheel drive, has the stock 4-speed with granny low--it's so low geared right now it could pull my house off the foundation, but since I just drive it, I dont really work it, I'd REALLY much rather be able to get up and go, but cruise at highway speeds without feeling like I'm gonna blow my engine...

Any help would be awesome, thanks guys!!