A liquid level transducer (10) for mounting to a cryogenic tank includes a mounting head assembly (14) for connection to the tank (12) and an elongate sensing probe assembly (16) extending from the mounting head assembly (14) and into the tank. The mounting head assembly (14) has a lower mounting member (40) connected to the sensing probe assembly (16). The mounting head assembly also includes a tank mounting member (42) with a central bore (74) and a transverse wall (87) located within the bore. An upper connecting section (60) of the member (40) is threaded into the bore (74). A seal (147) is positioned between the transverse wall (87) and the upper connecting section (60). The upper connecting section (60) has a corrugated feature that receives and deforms the seal to interlock the components together and increase the sealing surface area therebetween.