A trailer for use in transporting livestock includes platforms (24) that are vertically adjustable in order for the tailer to be adapted to transport different types of livestock. The platform (24) is secured to a number of multistage pistons which comprise a plurality of stages (34, 36) and a single cylinder (32). The advantage of multistage pistons is that the height of th housing only needs to be slightly greater than the length of the longest stage of the extension member. A cable extension transducer (38) is located adjacent to the cylinder (32) and has a flexible cable (40) which extends from a housing. The flexible cable (40) is secured to the end of the first stage (36) of the extensions member in order to accurately measure the overall length of the extension member comprising a plurality of stages (34, 36).