mileage wise, the v6 has more potential, but the v8 will probably outlast the rest of the vehicle, as those things never die!!! the ohv is good reliability wise, but its the a4ld... the 33s will be more friendly to the a4ld than the 35s... 4" and 33 sounds good, maybe depending on your gear ratio (what is it?), you could pull a junkyard 4.10 set and be good to go for the time being! ideally,, 4.56 will be the best, but thats $$$ that is unnecessary, so i would say 4.10 and 33 would be well matched... let us know your thoughts! and which lift kit are you going with when you go to 33s? if you pull a JY set, get a 4.10 LS and replace the clutch packs w/ the ford racing carbon fiber clutch pack, theyre really good for being a mostly stock LS! its not a locker, and never willl be, but its cheaper than most options... or go with a luckbox locker like pwoertrax no slip, etc..