I have a '99 4runner with a 3" suspension lift on it. I've seen others with the same lift who sit higher than I do in the back. Is it ok for me to replace only the rear springs? Or will it give me a rake? What about standard duty OME springs vs. heavy duty? Any suggestions? Thanks.

 

well, if you only jack up the back then you will get a rake.. as for the OME regular duty vs the heavy duty, you will get the same ride height, the only benefit is, if you load say 200lbs into the back, it stays at the same height with the HD and doesn't sag down like the regulars.

another worry would be if you give your vehicle another 3" of travel you might have to get new shocks.

 

I wouldn't suggest it because most likely you will have a serious dragster look to the truck.
Count on the 891 springs giving you about 2.5" more over stock and the 890s more like 2" (both with stock bumper)