I have a dana 30 with a 3.07 gear ratio in it, will 3.73 gears fit in the carrier or do I have to get new one?
if so how big can I go with the 3.07 carrier?
You'll need a new carrier for that. Since I'm guessing you won't be installing the gears and you're thinking of ordering gears, I wouldn't. I'd let the installing shop provide ALL of the parts so their warranty will cover both the parts and their labor. If they use the parts you provide and something goes wrong during or after the installation odds are good they'll just blame your parts.
yeah but I just finished swapping my rear axle and I don't feel like doing it again, anyway my dad said he'd pay for the regear cuz I did everything else myself