As you say certain gas shocks can change the ride height. Such as "air shocks" where the air pressure in the shock can be regulated to control ride height and action. Used by hot rodders a lot. Aircraft landing gear are in fact big air shocks with a mineral oil acting as the dampner and the nitrogen charge acting as the spring. And you adjust the height of the "spring" by putting the nitrogen precharge at a certain pressure(depends on the weight of the aircraft at the time of charging) or put a standard pressure on it with the aircraft on jacks. Sorry for the ramble but I couldn't help it. R. Giesbrecht 1972 Imperial _________________________________________________________________ The new MSN 8 is here: Try it free* for 2 months http://join.msn.com/?page=dept/dialup