<< Anybody know if these are available?  I'm talking about the things you stick the seatbelt buckles into to lock them.  My girlfriend has short arms, and it's a pain for her to reach almost all the way to the floor to fasten her seat belt.  I'd love to install replacements which would come up about as high as the seats themselves.  Does such a thing exist? >>

Earlier vans are so equipped. However, they usually have a different style buckle. You may have to switch the entore belt including the reel.

BenT