So what would happen if i went with the 3.55 with the big tires

RPM's will be lower at a given speed. I have 3.55's and 35's. When I am in O/D at 60MPH, the engine is turning 1500 RPM. With 4.10's, the engine would be 1725 RPM. "Off the line" performance would be lower, but top speed would be higher. 35's and 3.55's are very common, as it's easy to put big tires on compared to a gear set swap.

ok i didnt know if it would make the tranny work more or be hard on anything with the 3.55 but if your doing it with little bit bigger tires it must be ok

It is harder on everything, I won't lie. How much I can not say for sure, probably 15%. I pull my holiday trailer that weighs about 12,000# and it has handled it so far. Not all of it is hiway either, I tend to take it to the foot of the mountains to get away from everything. My trans is also built up to take more punishment.

What did you all do to your tranny?

All high energy clutches and discs, triple billet T/C, billet input, billet solenoids, and all new "soft parts" as I call them (o-rings, seals, gaskets, etc).

An upgraded valve body would be a good addition too. I recommend one from Suncoast.

After i get the gearing figured out i wanted to beef up the tranny a little bit and all of those are a good start thanks :tu:

I'm thinking about a Dunrite VB.

Well i had a friend put the gears in and some tie rod ends cuz they were in bad shape, I went will the 3.55 and now my 4x4 works :jump:.... so if you know anyone that needs 4.10 for a dana 60 let me know and thank you guys for all your help :tu: and now on to the next problem.