I have wanted to make something like this for a long time. I always felt that with the passenger side swivel seat base rotated 180 degrees there was a nice amount of room to slide the seat back closer to the dash.
I also felt there was a nice amount of legroom to be gained with a couple more inches of sliding the seat aft for the driver as well as additional passenger legroom. Pretty much at 5'11"" the driver seat is slid back as far as it goes to be comfortable. 6 ft and over and things are feeling a bit scrunched.
These seat rails provide the forward facing seat aft 2.25" of additional slide. They are easy to mount to the swivel bases we sell and while I have not personally installed these on a stock seat (non swivel) pedestal, the stock pedestal would require four additional holes to be drilled for these to work plus maybe a bit more mod.
The seat extension rails come with four nuts and washers to mount to the swivel base. The seat itself uses the existing mounting bolts.
CAVEATS: These are NOT crash tested.
They do, at least on 2009 and newer vans, require the door to be opened a bit to swivel the seat so the modified slide can clear the lower storage bin on the door. I do not know if the same is true for the 2008 and earlier with the smaller storage bin.
Price for each seat pair is $105 shipping included, $95 for will call/pickup. I have ten pairs made up as a first run to check for interest.
Let me know if you are in and we will work out the details! Thanks!