the heat shrink stops the cvd pins in the axle from falling out binding the wheels. i have the red metal pin retianer for them. the factory plastic drive shafts have pin retainers so the shafts don't come loose. the pins in these punisher shafts look good so i don't think they will fall out.
rcc is where i end up when i'm doing research on crawler stuff. lot of good tried and tested info on there. i read the whole creeper section at least twice when i first got my creeper it helped more than i could explain. it's getting down to a hand full of parts then the creeper will be done. i can't wait.