I have a 1984 22r pickup. Its on 31x12.5x15 tires right now, i want to jump up to 35x12.5x15 but buddy of mine told me that i don't want to go that big on the stock 4.10 ratio because 5th gear will become basically useless. I am brand new to working on cars and know extremely little. Im learning as i do doing basic maintenance on the truck. Is it a total pain in the ass to replace the gear pinions and stuff? How much would it cost me if i payed a shop to do it? Anything helps, thanks.