What are the reference points for setting ride height?

I have the spec's for setting the ride height. If memory serves it's 3 3/4" inches in the front and 4 1/4" in the rear. My concern is where are those measurements taken? On the frame members in line with each axle? I can't see any reference marks under the car, or obvious measurement plates. Then again I don't know what to look for either. Any suggestions?:banghead:

Jerry in the GTS manual it states:


Ride Height

*3 1/2" in front (from bottom of chassis to ground) at front axle ceter line.

*4" in rear (from bottom of chassis to ground) at rear axle center line.
This is on page 61 in the GTS owners manual that Jim (Gatorac) has available for download on his site. The link to the site is in his signature.

The overview doc I have from John Leverett states:
FRONT 3.75" REAR: 4.250"

The Alignment Adjustments Road Atlanta doc I have states:
Front 3.5" Rear 4." to 4.25"
Hope this helps,
Brian

PMed you on wheel speed sensor pics.