If I were you, I would contact the Texas Department of Transportation and ask some questions.

Their web page says this:

Vehicle Titles

Whenever you buy or sell a vehicle in Texas, state law requires the vehicle be titled and registered in the buyer’s name within 20 working days.

If you buy from a dealer, the dealer is required to file the title papers on your behalf.
If you buy a used car from a private party, visit your county tax office and complete a title application [pdf, 2 pages, 113kb].
When you file the title application, you must pay the motor vehicle sales tax, which is 6.25 percent of the purchase price. (Note: Effective October 1, 2006, a new law may impact the amount of sales tax you pay when you title a used vehicle.)
You must also provide proof of liability insurance when you title and/or register your vehicle, so take your insurance card.
If you sell your vehicle, ask the buyer to transfer the title to his/her name. Accompany the buyer to the tax office if possible.
Note: You may be considered the owner of the vehicle until the title is transferred out of your name or you submit a motor vehicle transfer notification [pdf, 1 page, 130kb]. This notification lets us know you no longer own the vehicle.

The beauty of the PSD transmission is that it is extremely simple compared to regular auto or manual transmissions. Just one single planetary gearset, no gear-shifting wear-and-tear, no hot-running torque converter, no clutch, no CVT belts.

How the PSD transmission works: http://eahart.com/prius/psd/

Cars that use the PSD transmission:

- Toyota hybrids (Prius, Camry Hybrid, Highlander Hybrid)
- Lexus hybrids (GSh, LSh, RXh).
- Nissan Altima Hybrid (licensed Hybrid Synergy Drive from Toyota)
- Ford Escape Hybrid (independently developed).

The Toyota Prius has just 22 moving parts in its PSD transmission. That’s compared to 100+ moving parts in a typical 4-speed automatic transmission with torque converter. The lower part count means higher reliability and less maintenance– PSD trannies require a fluid change every 60,000 miles.

The PSD transmission has proven to be extremely tough– New York City has been using the Ford Escape Hybrid as taxi cabs since 2004. Most has racked up 200,000 miles with no problems, withstanding the daily abuse dished out by cab drivers. Vancouver has been using the Toyota Prius as taxis and have also had no problems.

Take note that not all hybrids use the PSD transmission. Honda’s Civic Hybrid uses a belt-driven CVT transmission, while GM’s Saturn Vue Hybrid and Aura/Malibu Hybrids use a conventional 4-speed automatic transmission with torque converter. The big GM hybrid SUVs use a complex 2-mode transmission which is a 4-speed gearbox with 2 clutches that engages a dual-motor electrical drive. Only the Toyota, Lexus, Nissan and Ford hybrids use the Power Split Device.

Hope this helps.

You will need the 700r4 trans and torque converter along with the slip yoke.
You will need to have your driveshaft cut down 2.5″. The overall lenght for the 700r4 is, where the th-400 is 28-1/4″

Then you need to address the front U joint. The th-400 will use a 1310 or 1330 U joint where the 700r4 uses a 3RN joint. If you are having shaft cut down you can have them to put a 3RN end on it or you can go back with the 1310 then use a 1310 to 3RN conversion U joint

You will also need to move transmission crossmember foward and maybe drill new bolt holes in frame. The face to mount on the 400 is 26-3/4″ where the 700r4 is 22-3/8″