I did a fair bit of work installing stuff under the seats in the new-to-us 06 LJ. My wife is 5' 4" tall, and was having trouble seeing out the front window. She had an old rug on the passenger seat for additional height, which was not a good sign.
So, I bought a seat riser kit from Buchanan Precision Machine, see
http://www.buchananworks.com/html/jeep_parts.html. I'm 6' even, so seat height was not a problem. They recommended a 1.5" seat riser kit as something that would help my wife out a lot but not be too tall for me.
Additionally, on the passenger side I am installing a Yaesu FTM-10/R dual-band ham radio. We have slide-and-tilt front seats, so space is very limited. I only wanted a 2m-band radio, which would be cheaper, more powerful and more robust. But the FTM-10/R is tiny (popular with motorcycles) and has a removeable faceplate.
Anyway, here is a picture of one of the seat riser blocks (black anodized aluminum) and radio mounted mechanically on the passenger side.
Although the faceplate it currently on the radio, I'll remove it later. Here is a picture showing how the radio is mounted mechanically.
It's very simple. I made a mounting pad out of a piece of 1/4 x 4" aluminum. I cut about a 6" piece. (With a hacksaw! Took about an hour, but got a straight cut and some exercise.) The original plan was to have a 12" span between the front seat mounting bolts, but I decided against it. I drilled and tapped some 10-24 threads into the plate. There is a Yaesu bracket that attaches to my plate and then the radio is attached to the bracket. This is similar to how I mounted a ham radio under the passenger seat of my KJ, except I used a thicker plywood piece.
To alleviate vibration I stuck an old, thin (1/8") neoprene mouse pad between the aluminum plate and the floor.
Here is another picture of the passenger side showing the radio and all four seat riser blocks.
On the driver side I mounted the seat riser blocks and a Tuffy security drawer. Here is a picture of the assembly:
One problem with the combination of the seat riser blocks and the Tuffy drawer is that you can't use the bolt-block plate that obstructs access to the front right mounting bolt. So it's not as secure. That said, now that it's in it looks like with the 1.5" riser kit I could mount it upside-down and it would work. Or I could fabricate something similar. I'm not going to worry about it now.
It's all bolted in but nothing has been tested other than to sit in the seats in the garage. Tomorrow we're going on a combination Jeep trail ride and hike, so we'll see how it all works. My wife is giving positive feedback about the additional seat height.
Still a fair bit of work to do to finishing installing the ham radio and a CB radio. Briefly, the final plan is to mount a pair of antennas on TeraFlex rear tail-light mounts. For power I plan to mount a Painless auxilliary fuse block and a ground bus block on a plate near the unused master clutch cylinder hole. (Ours has an auto tranny, so that wonderful big hole and two bolt holes are available for electrical stuff.)
Oh, in the last photo you can see some rust on the seat mounting hardware. It looks like the previous owner hosed down the interior or something and the seat hardware is regular steel. That's the only rust issue that I've noticed. Not a big deal as long as it's just the seats.