I'm using losi 8ight 2.0 buggy RTR rear shocks (2.0 truggy front shocks are same length) on my e-maxx. Had to open up the upper rpm arms the shocks pass through cause the springs rubbed and I had to open the upper holes in the tower for 4mm screws, Other then that they bolted right on. I'm only using 4 for now but it needs 8 b/c I can't find stiff enough springs for the 4 shock setup which is just a tad to soft.
Here's a build thread on my e-maxx.
http://www.rcuniverse.com/forum/m_10465113/tm.htm