so on this 01 dodge i just bought it has 3.54 gears, i am very used to the 4.10's in my 12 valve, so it will take a while for me to get used to these gears and the difference in motors. but anyways i was lookin up the specs for speed and rpm ratio here http://dodgeram.org/tech/specs/axle/47auto.htm ... 4.10's are at 2100rpm on the highway and 3.54 are between 1700 and 1800rpm at 65. well the truck isnt registered yet but i have taken it down the road a few times, and it seems like at 65, its a hell of a lot closer to the 4.10 ratio. theres no way its at 1750 at 65, and i checked it with a GPS so the speedo is correct for the 245 tires on it. i just dont understand, it says it has the 3.54's in the glove box so it deff must have them gears. Say i hit the overdrive switch at 50 it will downshift and be revving to about 2100-2200 approx. idont know if its me or i just need to drive it more to see or what, it just seemed not to be right. any ideas?

 

I need to check but I'm defiitely below 2k while going 65, might be somewhere around 1800-1900. This is on both trucks w/3.54's, 99 2500 4x4 with 245's and a 98 3500 2wd with 235's.

 

I beg to differ, In my 04 2wd with 4.10's I rev at 1900 at 65 mph, with the 3.54's you should be down around 1650-1700 rpm.

 

my 2000 5 speed with 3.54s at 2000 rpms 67mph my brothers 2002 with 6 speed and 4.10s at 2000 rpms 60mph

 

forgot to say that both trucks have stock tires 245s

 

my 99 with 265s runs 2K @ 60 and about 2100-2150 @ 65

 

With my 99, 3.54 Gearing and 47re Tranny. I run 110kmh at 2000rpm (about 68mph), probably around 1900 for 65mph

Smokeitup: You have the 48re tranny, the gearing might be different in it than the 47re tranny (just a thought by me).

 

yeah i run about 1950rpm's with my 4:10's at 65mph always have....now this is in my 12v with built auto

 

Did you check the tag on the diffs? The prior owner might have switched them out for something else....

 

Checked it out last night and I'm exactly at 1800 while going 65mph. I'm not sure but in your case (48RE) might be a little different. I'm going to check my diff tag anyway just to make sure.