Friend of mine told me if I did a leveling kit in the front I would need rear blocks or it will sag......any truth to this....thanks

 

Yes, under load it will sag. Unloaded it won't. But if you do blocks as well, you will end up with a bit of rake again.

 

This is with a front 2.5in leveling kit and 3 inch rear block with no load.

 

A front leveling kit is not going to change the rear spring rate at all. A leveling kit is not going to cause the front coils to sag either. The rear springs will compress under load the same whether the front is lifted or at factory ride height. the front is The reason the trucks come higher in back is so when you haul a load or trailer, the rear will compress and the truck will ride close to level.

*Settle- When a spring is new, over time it will settle to a normal ride height
*Compress- When loaded, the spring will compress but will come back to the normal ride height once un-loaded.
*Sag- Over time springs can sag under normal use, reducing their lift and normal ride height with no load. This is when springs are worn out.

 

My truck has only 1 1/2" rake. I ordered a 2" AS and their 3" block. That should give me factory rake. Some trucks are different. Measure center of wheel arch to ground front and rear. That should help.