I'm still running 245/75's, and will continue to do so for at least another year or so (until the MT/R's I have are toast). My switch to 4.10's happened a little over 2 weeks ago... and I
did notice the difference right away after regearing.
Was it a HUGE difference that others report? No, it wasn't. BUT, I'm also not running 265/75's like some of the others. I assume that's the major reason I don't feel it's that much of an improvement. I do notice more "get up and go" off the line. And while I have noticed a little bit of a fuel mileage improvement from cruising around town, I lose some of that on the interstate/highway drives.
My reason for regearing was because I needed to the have the pinion bearing in the front differential replaced anyway - I didn't see the sense of opening everything up, and not upgrading, to a degree (too bad a locker wasn't in the budget
).
I suppose what I'm saying (
from my own personal experience) is... if you run a larger tire (comparable to 265/75) with 3.73's before you go to 4.10's, you'll notice a bigger change with the regear. If you're running something like 245/75's with 3.73's before going to 4.10's, you'll notice a less-dramatic change... but you
do notice it, nonetheless.
Yep you will feel just a little less due to you having the 45RFE trans,if you had the 42RLE trans you would have noticed a much bigger difference.
I know my KJ's 3.7 liked to spin at about 2800rpm's on the highway,with 265/75's I had to do 85mph or more to get in that sweet spot as the engine would only run about 2400rpms with 3.73's and lugged badly.After the 4.10 install the engine would turn 2700-2800rpms at 78mph and all was happy.Now running 35" tires and 5.13 gears I'm right back in that 2800rpm sweet spot at 65mph.The slower speed does not concern me as 65mph is plenty fast enough with 35" tires anyways and caster angle comes into play big time at those speeds with 35" tires and I have to set my caster for front pinion angle as rotating the inner C's is a job that I don't want to ever do.Plus the caster angles I'm running now make for very easy turning at low speeds but can be down right scary above 75mph.