I've never really heard of anyone having problems with new CVs once they are replaced. I've had several Napas and a couple 4wheelparts CVs and they break on the trails, but none of them ever leaked except my original stock ones. The stock CVs just get used to sitting in one position for about a decade and when you suddenly change the angle, they don't like it. The CVs themselves will still usually last a long time though even after they start leaking, so I would just try to clamp em like Gerdo suggested. Hell, I clamped my original CVs when they started leaking like yours. Then the boots just tore open after a while, so then I wrapped duct tape around them and they were good for another month or two. Then the boots just fell off altogether. I still drove mine through an entire snowy and muddy winter with no boots at all and they still never did break. I just replaced them for good measure.