This may sound like a really dumb question, but I was wondering what is the differences between the skyjacker kit and the skyjacker system. They are usually about $500 difference and it doesn't seem like much is different besides the rear springs get replaced on the system. Is there anything that I am missing? And I know the kit calls for 37x12.5x17 tires on a 17x9 rim with 5in backspacing, but could I get away with running 37x13.5x17's on a 17x9 with 4.5in of backspace? I am not the biggest trail person so I won't be flying around in it and beating the hell out of it. It is more or less my DD that likes to occasionally play in the mud or take a shortcut that is not an approved road by the department of transportation.

 

That's probably the only difference, just the springs instead of theblocks. Springs are better than blocks, hands down. And if the kit calls for 5" of backspacing, get 5" of backspacing.

 

Yup, the more expensive of the two comes with leafs, the lesser uses blocks. Leafs are better, but I've always had blocks, used to run off-road as much and as hard as anybody who uses their daily driver to do so, and never had a problem, although I have personally seen someone snap a "U" bolt and lose their block, but this was on a weekend only play truck doing some things that any sane person would not do with a $30k+ daily driver.
Specs given are ALWAYS the minimum specs, if it calls for 5" of backspace, you need 5" of backspace or you'll need to do some body trimming...

 

I see. So if I was to go with a 5 or5.5in backspace would itbe possible to clear the 37x13.5x17's without trimming? I was just wondering because I want the biggest tire in the smallest space possible. I like to see all tire and no wheel well.