i would go with 4.56 if you r planning a t56 swap for sure at 100 it would be around 1800 to 2000 rpm,just depends on tire size.

 

245/75/16 tires with 3.73's at 70mph in 5th nets around 22xx rpm in my truck. Decently fun around town, but first gear winds out awfully quickly. Not that its a pain, just an observation.

I'm fixin to swap in a T56 and am looking at 4.56's. You don't want to do a gear swap twice, so I guess first decide on what tranny you're putting in, then gear it from there.

 

my tire is a littler taller and at 70 Im a 2100 or so...but I just recently found out that my truck indeed has 3.73s and I coulda swore that it had 3.23s...I do know how you drive your truck man...my truck is such a pig and I live in somewhat or a city so shifting constantly and I need more low end...I mean if you do a lot of highway driving your good to go but even still...when I hit a hill of any decent size I best make sure my foot is burried to the floor to make sure I get up or else 4th here I come...I still need a tune so I really hope that will help me out!

 

Thanks for the info. That has been really really helpful. I will see if anyone with 4.10's has any input. So far going to a 3.73 would only add 2k (2200) or so to my cruising speed in 5th. 4.10's would only put me at 2500 maybe.

Also a T56 is very far down the road for me. There are no late model places here, and spending 1500+ for a used one just doesn't seem right. So i am just stuck between a rock and a hard place on this one.

Dustin

 

ــــــــــــــــــــــــــــــــــــــــــــــــــ ــــــــــــــــــــــــــــــــــــــــــــــــــ ــــــــــــــــــــــــــــــــــــــــــــــــــ ــــــــــــــــــــــــــــــــــــــــــــــــــ ــــــــــــــــــــــــــــــــــــــــــــــــــ ــــــــــــــــــــــــــــــــــــــــــــــــــ ــــــــــــــــــــــــــــــــــــــــــــــــــ ـــــــــــــــــــــــــــــــــــــــــــــ ـــ
4.56

 

Whats with all the lines?

Dustin

 

Well, if anything ill just keep your mind open to the oddballs. Im not impressed with the 3.73 in my truck, the pull it has in 1st and 2nd is amazing, seems once i hit 3rd i slam into a brick wall til she gets back in her powerband, and 4th is similar. I plan on going to a 4.30; i think at this point 4.10 would be a waste of a rear-end overhaul, and 4.56 would be a tad overkill, so im gonna settle for a 4.30; even if i decided to throw a different tranny in it down the road (say a T56 or so...) i'd have a decent gear in the back for that also.

http://www.f-body.org/gears/

That helped with my gear selection as i was able to input what gear ratios my trans has, versus tire size, versus rear gear. I then figured out what RPM range i wanted my truck to be in for shifts and a 4.30 will work perfect for what im aiming for, so ill just see if all this thinking works out in the end...

 

keep us posted on that gear selection