i've stopped using seals on my tunnels altogether. they always seemed to be what leaked. now i use the next bigger size outer sleeve/tube that my throttle cable outer sleeve/tube will JUST fit into. i use sullivan #503 & #507 cable sets for my pieces. drill the radio box for the larger tube, & epoxy about a 1 1/2" piece in place. then slide the throttle cable sleeve into it as far as you need to, & ca in place. use a small piece of fuel line over the connection for some support, & ca in place. for CABLE steering, i use the outer housing off the small sullivan cable that i use for my throttle. forget which #, either 503 or 507. the smaller one
...... about the same, drill box, insert tubing (about 1" pieces or so), & epoxy in place. cut your cable long, run it through the tubes. slide some SMALL diameter heat shrink over the cable & tube, & shrink to seal. only leave about an inch of cable sticking out, because when you heat the heat shrink, you will mess up the plastic coating on the cable - don't ask me how i know
. pull cable on out, clip off the ends you just melted, & rig as usual. simple, light, VERY inexpensive (i'll bet most of us have everything already in our shops), & DRY. ask anybody i race with in dist. 12, my radio boxes stay dry. even after a flip in a race & sitting upside down for 10 - 15 minutes, i don't have to untape to dry it out, to finish the day. IF i stay right side up, i may not untape all weekend!!!!