Toyota Nav Help for an 2004 DC w/JBL Audio

[enrtut]

Hello all. I am interested in replacing my stock single CD stereo head with JBL audio and steering wheel controls with a Toyota nav unit. In searching I see that the e7006 should be plug and play with my set up, with the exception of needing to wire an additional speaker in for the turn by turn directions. However, is the E7006 the only unit that is plug and play in my truck or will the other models work like the e7007, e7008, e7009.
Additionally how difficult is the installation if one of these new units, they don't appear to be to difficult, but again wanted to ask before I get in over my head. Any help or opinions are appreciated. Thanks for the help.

Also for what it is worth, I do not have any stock DVD entertainment systems or anything fancy like that in my truck, if that could complicate any matters of instillation.