Ball & Trunnion rubber boot - '63 valiant

You can get the boot-and-clamp kit from www.oldmoparts.com . He officially doesn't support Mopars newer than '62, though many '62 parts fit newer years as well. The boot package you want is the one listed for '60-'62 Valiant and '61-'62 Lancer. This same boot was used on Australian RV1, SV1, AP5, and AP6 Valiants, so you may well be able to find it locally. You may also want to consider doing away with the ball-and-trunnion front joint altogether; see here.