SmokeShow96

MDMIKE,

I have incredible take off so lower HP feels like a lot more than you actually have. Top out speed is around 90mph. I couldnt trade with you anyways cause you have the dana70 rear and I have the Dana80. I would have been willing to trade but with pulling in mind in the future for my truck I dont want to go backwards in the rearend you know what I mean. Thanks anyways.

SmokeSHow
Mitch Ratliff

Oakman

Hey guys, Ive been around here for a couple years but I'm guessing my account got closed since I havent posted in a while so I just registered under the same name again.

I did the swap from 3.54s to 4.10s at the beginning of this year. I'm running 38"s so I needed them to save the rest of my drivetrain and it put my rpms right around where they were with stock tires and the 3.54s. Anyway, its not a cheap swap (either direction) if you go with new parts. When I priced the rear, it was over $1100 in parts alone (Dana 80). I went with used parts from a Ford dually, but they were a PITA to set up. I havent had a lick of trouble from them though and Im not easy on the skinny pedal. The Dana 80 split is 3.73 and down so you need a new carrier, but the front is fine. Also, you're going to need master install/rebuild kits for both axles to do it correctly which will run about $200 for the rear and $100 for the front. Anyway, I guess my point is...I still have all of my 3.54 parts from the swap sitting in my closet if anyone here wants to buy them. I wish this thread was around when I was doing the swap so we could trade straight up, but Id like to get around what I bought the 4.10s for since I was about to put them up on ebay before I saw this. I dont want to turn this into a 4-sale thread, but PM me or email me if your interested.

chris_mojo@yahoo.com

Chris

walexa

Hey guys, did the swap. I purchased the gears from Oakman and had the rear end done a couple days ago. They couldn't do the front end swap yet, so they disconnected the electronics and the vacuum hose from the front disconnect to prevent it from accidentally engaging. I can honestly say that I really like the 3.54's over the 4.10's. I also killed the KDP last weekend and that sure is peace of mind. Mine had worked out a little over 1/16". The TST kit was very straightforward......I would have to say the hardest part is working the fan and shroud back into the truck after everything else is done. Nothing hard at all, just a little time consuming. I think it took me about 5 hours, but I was not rushing at all. Back to the gear change, I was getting 16 mpg pretty consistently, but since it was only tuesday that they did the swap, I don't have a current account of what my mileage is right now. I still need to set my valves and get my timing bumped up and I'm hoping to see some improvement in mileage from that as well. I will post again after I get a tank or two run through to get my mileage average with just the 3.54's. Thanks again for all the advice.

Waylan

CarlJensen

I have a question for you guys, the tag under the hood says 3.5 ratio, not 3.54 and I don't know why. Anybody know what it really is?

RowJ

Nobody seems to know for sure...read here for how to find out,
https://www.dieseltruckresource.com/...threadid=55611
RJ

walexa

I just thought I would update this post as a FYI:

I have now been running the 3.54 gears for 3 months and overall, I have averaged .2 mpg better. I bought the truck on 8/24/04, and up to the gear swap on 11/30/04, my overall average was 15.32mpg. From 11/30/04 up until I added the #10 plate, my overall average was 15.48mpg. My best fuel economy with the 4.10 gears was 17.0mpg, and my best with the 3.54 gears has been 18.0mpg. Yeah, I know, kinda sucks. Either way, I still prefer the 3.54 gears over the 4.10's.

I believe something is not tuned correctly with my engine.....just not sure what it is. Once I have time to adjust my valves and advance my timing, I will be able to eliminate them as possibilities. I will post back if I ever find what is holding my fuel economy back.

Waylan

MDMIKE

I guess I'll jump back in this one too. I'm still considering swapping to 4:10's from the 3:55's for a few reasons. I'm running 315's (35's) on the truck with a 3" spacer in the front and add-a-leaf in the rear and I never see myself going any smaller as far as tire size goes. Most of my driving is done in between 45 and 55 mph and I feel like I'm lugging the truck around everywhere I go. I'm tacking just under 2 grand with the TC locked up at 70 MPH on the highway. I feel like I need more gear on the open road when I do tow the trailer (maybe about 5k Jeep and trailor). If the above post is true and MPG only drops 1 mpg between 3:55's and 4:10's this would make my decision a no brainer. I'm assuming that the majority of the guys that are unhappy with the 4:10's are driving duallys with factory size tires? Is anyone out there running an auto truck with 4:10's and 315's? If so, what kind of fuel mileage are you getting? Any advice or thoughts are much appreciated. Thanks!

MIke

1dslram

There is 372 gears available. For me it was enough lower to keep the R's up while towing and not as low as the 410's. I drove several trucks with the 410's and it was just to low for me, I had the 352's and that was just a tad to high on the street and at the drags, I had the 372's inatalled and had a pro-lok rear added at the same time. Now I am much happier.
Bruce

mr T

how do u guys know what ratio u got in the back?? i have never driven more than one CTD so i cant have nothing to compare...where do u look to see if i have 4.10's??

walexa

If the truck hasn't been messed with, it should be under the hood on a label, as well as on a metal tag hanging on the rear diff. Those are the 2 places it was listed on my 98 12v. Not sure on other models though.

Waylan

Ray,IN

Hi all! I've been in Florida all winter, and feel like I've missed everything. I don't mean to highjack this thread. Hopefully my situation can fit into the original topic. I have a stock 1996 CTD w/ 47RE tranny. The AT is modified with BD parts and TC. I now have the stock 3.55 gears, and with the anticipated 5TH wheel RV we may buy, I feel perhaps I should switch to 4.10 gears. What are your opinions? I was offered an entire banjo assembly with 4.10 gears for $200, but the guy wants $600 to perform the switch on my truck only.

pittom

If you adj your valves it could help a lot. I was geting 10-12 mpg,did my valves and all (all) filters now i get 15-17mpg with 4.10 and 31" tires. going to put 35"tires on insted of changing my gears, this way if i ever have to pull something heavy ,just put the small tires on.

RedD

Personally I like the 410s with 255/85s on If I know I have to carry more than a ton give or take for a long ways I put the 235s back on.On my dually with 354s I have 215s on it and when Im loaded to the gills just keep her in direct drive.The 410s are also much nicer for control with stopping or slowing down eh! Just throwing my 2 cents in if i had the money Id put a splitter trans between all three trannies and t- cases they are the ticket as I once had one.

y22man

Look here for a nifty spread sheet. Edit for your tire size with your tranny and you can see the differnce in RPMs at differant speeds and trannys. Thanks klenger!

http://www.klenger.net/dodge/general...calculator.xls

gunracer1

i have 3.54s with 285s and a nv5600 and i still wish it was geared a bit taller. i think i would be very happy with 3.08s or maybe 3.23s. i tow up to 30k gross and i have never needed deeper gears, even when i had the 5 speed. but the gsk and 1k torque make up for a lot of gear.