I have a 95 4runner 3.0 v6 with a 6in trail gear lift. A couple of days ago, I was looking at it from behind and noticed that the truck was leaning toward the passenger side. After reading a bit i saw that because the springs are soft and the gas tank is on that side, it kinda overloads the springs and causes the leaning. Any way to repair this and if so, about how much will it cost me? Does this affect the ride/ capabilties of the runner drastically?

 

This isn't a leaf spring question because you do not have leaf springs. You have coils. You can stick a spacer in or upgrade/replace the coils, it's not that big a deal.

 

He has a 6" trail-gear kit, which means he has converted to leaf springs.

This is VERY common for trucks and 4runners stock and with aftermarket suspension.

Some people have swapped springs from side to side and have had success but not always.
How many inches of sag are we talking? If its not much, I wouldnt even bother, also the truck tends to even out when there is a driver in the truck

 

Thought of that after I posted, but couldn't find any info on that lift. Those leaves must be lift-specific, then? Toss a shackle on one side or something maybe.

 

The runner leans about 2-3 inches. I just don't want to shove the spring up into the frame and cause serious damage.

 

Assuming a SAS up front? If so, did you add the spring perch spacer on the front axle driver's side perch? If not, do so, that may help level things out and yes the front springs being off can make the rear end sit funny. And try swapping the rear springs side to side to even out the sagging. Could be one side settled faster than the other and swapping will even things out. If that doesn't help, you could add a leaf to the sagging side to stiffen it up a little.