Ok......... So after reading the 3.21 gearing post, and talkin to pyro, I have a couple of questions about gears and the 45RFE trans that I hope you guys can help with.

I thought that I had read somewhere on here that you can change the 45RFE trans into the 545RFE trans just by getting the TCM that comes on a vehicle with the 545. From what I do remember, the 45 has a 5 speed gear however the TCM was never programmed to use it. So thats why its only a 4 speed. Does anyone know about this?? Can I plug in a 545 TCM and just like that, got myself another gear??

Also, I am thinking about swapping out my stock 3.55's to possibly 3.92's. The gears I will be getting will be factory gears, not aftermarket. I have three questions about this.....
1) What size are the axles come on a 1500 in 2002? I think dana 44 fronts and chry 9.25 rear... Is this correct?
2) What gear sizes were offered? Is there, for a half ton, anything higher than a 3.92?
3) Has anyone ever installed this themselves? If I could install this myself, It would be a *******ly free modification to my truck. Which is how I like it! If someone has done this, any special tools required or anything of that sort? I would appreciate any information on either of these subjects, as well as pictures, if you did the install yourself, if you would be so kind. Thanks for your time, and sorry for the long post!

 

You will not notice much difference from 3.55 to 3.92. I went from 3.21 to 4.10 - that was a difference.

 

Is 4.10 a factory offered gear ratio for a half ton? I dont need that much of a difference, however with a 4.7, I would like to upgrade. Like I said, the gears I will be getting are factory gears. I know someone who can get me some. So whatever gear options there are for my axles is what I am going to weigh....

 

yeah can do the gear install yourself, but i would recommend having some 1 to do it, your going to have to assemble and disassemble the rear end many times, sometimes you get lucky and the factory pinion shim does it for the new gears, to get the correct gear tooth contact pattern, on the other hand you may have to take everything apart again press off your new bearings without destroying them and add a shim or to then reassemble..kinda sucks when its under the truck

 

if you have never done a gear swap before, i wouldnt attempt to do this yourself. there are way too many things involved that could go terribly terribly wrong. and no, 4.10s were not a factory option for the half tons, only the 3/4 and possibly 1 tons. and your rear end is a 9.25 chrysler.

 

ok if the 4.10 is out of the question, then i assume that the 3.92's are as high as I can go then?

And... I suppose I will not do the install myself. I hate the smell of rear end dope anyways....

 

with 3.92 you wont notice any difference from 3.55. 3.55 to 4.56 I noticed some difference.

 

Pulling a trailer now with my truck is pretty lame. I am gonna get the gears for free.... So even if its not noticeable while driving, I would prefer it for towing. It makes it easier on my truck. And 90% of my driving is city driving. lot of stop and go. So for maybe two hundred or three for an install kit and labor, I think it is worth it in the long run.

 

If you are running the same tire size, then a swap to 3.92's will show a slight improvement. Heck, my 2500 is rated to tow 2,000# more with 4.10's over the 3.73's and that is less of a change.

You have the 9.25" rear axle and the 8" (205mm) front IFS diff. No Dana 44 in the front of an 02.

 

I never even knew they made an 8 inch diff. But good to know! Now I can get the right gears the first time! haha. Thanks LiftedAstro.