Yes, that is the IFS mount. As far as the position, you have to figure out how far forward it needs to go so the steering arms are straight and not too far forward or too far back... There is not a "set" position. The larger rectangle with the hole is for the front spring perch on the drivers side to level the axle out if its a hair short on that side. I just did this kit and didnt use it. The piece right below it, there is actually two of them. It acts as a gusset on the front spring hanger above each shackel mount.. maybe someone has a picture of it they can post for you. As far as the shocks go.... mine were all the same size also. They all worked. See my thread,.. I installed the the trail flex kit also.
http://board.marlincrawler.com/index.php?topic=14309.0
Your truck looks nice.. I like the color 
Thanks for the first Informations ....
i will look on your thread and maybe i have more questions
yes the color is nice
eyecatcher 
and i think when we have the Kit Install i will start Project-Buildup-thread
