A few times I've seen folks wonder what height their truck started at, since they forgot to check before a lift. I was at the dealer yesterday, so grabbed bumbers off 4 trucks they had. I used a regular tape measure, from ground to fender, using the center of the hub cap to keep the measuring point as close to similar as I could. Height is in inches (I'd have preferred millimeters for more accuracy, but only had an Imperial tape measure with me)
Truck 1 and 2 were Prerunner TRD Sports. Truck 3 a Sport 4x4, and truck 4 a 4x4 (non off road or sport). All were in the lot, I assume none had the rear TSB performed.
Driver Front; Pass. Front; Driver Rear; Pass Rear
1) 34 5/8, 35, 37, 37 1/8
2) 34 3/4, 34 7/8, 36 3/4, 37
3) 34 3/4, 34 3/4, 36 5/8, 36 5/8
4) 34 1/8, 34 1/2, 37, 37
I lost my measurements, but on my truck (4x4 Sport) it was pretty similar- high 34-low 35 inches up front, I think low 37's in back. That was WITH the TSB rear leaf though.
As you can see, even the trucks themselves have a lot of variation. I think it's safe to say that IF you didn't measure your truck first, you would probably be OK with a target height in mind and just going to that, instead of worrying that you may be a few tenths of an inch off.
Hope this helps someone!