So, how can I find out which spindle I have? Probably the easiest way is to turn your steering wheel all the way to the left (drivers side), should look like the image above, find your spindle. If it is dark, a little rusty looking it is a cast iron spindle. If it is silvery or shiny it is a aluminum spindle. If you have any doubt get another opinion or ask you mechanic.
Here’s the deep drop for your Tahoe, Suburban. A three inch front drop with Calmax control arms and a four inch rear drop with coil springs and supporting hardware. The 3″Calmax control arm set has both upper and lower control arms. The lowers give you the 3″ drop while keeping your factory coil. Great news because with your factory coil you get full suspension travel and a great ride. The upper control arms optimize the ball joint angles and more importantly allow you to align your lowered Tahoe, Suburban to original GM specs. This is really very good because it means you can also do a little performance alignment if you want to kick up your heels a bit.
The rear is basic and easy, install a set of 4″ engineered coil springs and use the hardware kit to step the trailing arms down away from the frame, and install the swaybar endlinks to keep it out of the way of the other moving parts!