ok, it's my undestanding that a 4th gen driveshaft will pop right in my third gen, but i'm not sure about the u joints...i'd like to use solid ones but for which application(3rd or 4th gen, even in third gen the u joints differ in sizefrom the steel and aluminum) do i get them for? are all 4th gen driveshafts aluminum(v6-v8)? any pointers would be appreciated before i swap 'em, if i can? thanks!