Captain Coop

I have 35s and 410s right now. I am seriously considering switching to 3.54. Is this combination tolerable. I dont tow very much. I have an EZ but thats about it. I plan on getting a comp box at some point. I already have gauges. How will it fair with the EZ. I hear it makes your EGTs go up and your boost go down. True?

Homestead

I enjoyed my 35's when I had them. I thought it was a great combo with my truck. Highway mileage went up, city went down.

I'm going back to 35's because I'm mostly highway driving now. Around town tends to drag you down a bit but I never did mind it. I towed like I always did with the 35's, never an issue unless you go real heavy and in my case I put my 265's back on.

Jeff

bnold

If you are not towing a bunch and not really heavy 3.54 and 35s are a good combo...

I towed too often and heavy and dropped to a 32ish

Captain Coop

I do a lot of driving on the highway and I dont care as much about the milage as I do just going so dang slow. I cruise at 2200 RPMs or so and on the GPS on my phone its right between 72 and 73 MPH. Kinda tired of that. I dont like to run any more revs than that. I have an 01 5 speed and I think I have the tow package. Does this mean i have a dana 80 in the back and 60 in the front?

Andy505

your 5 speed is what gives you the dana 80 in the back and 60 in the front. I'm not sure though on a manual what the towing package consists of.

For 94-02 all cummins manuals had an 80 rear axle. All cummins 4x4 had a 60 front axle. If you had an auto cummins then you got the 70 in the rear. Unless you had a 3500 in which case you always had an 80...even with the gas motors.

Captain Coop

what do you guys think a shop would charge for labor in swapping them. Im not confident enough to try something like that. Then I guess i could the old ones for a little bit of $$

Andy505

I swapped my 4.10 to 3.54 a few months ago, overall including parts was roughly $1500. here is a breakdown of the price

New ring and pinion front and rear $200 (from the classifieds here on DTR)
New carrier for rear $335 (ebay)
New Front Bearings about $130 (ebay)
New Rear Bearings about $200 (ebay)
Lube and misc. about $50
Labor at a local shop $550

Mileage went up. I couldn't get better than 18 before and now I can get 21. Plus you can sell your old gears and carrier and recoup some of that money.

ellerman

You sure this is true? I thought only 6 speed manuals got the 80 and auto's/5 speeds got the 70. 35's and 3:55's are fine if you don't tow real heavy.

RowJ

5 speeds got a D80 also!
Captian Coop - with a 5 speed you can control rpm to deal with 35's around town. On hwy, with my auto, I get about 1800 rpm at 70 mph.... 2000 rpm at 80 mph, which is sweet. You will get slightly higher rpm due to 5th gear ratio.
As mentioned, if not towing over say 15,000 lbs, go for it.

I was quoted around $1,500 also..... half labor....half parts (new bearing in the rear, only). That was in L.A.
Labor probably cheaper in more rural area! Where are you?

RJ

G1625S

As was said, if it's got a clutch, it's got a d80. RowJ is correct---staying under about 15k behind you and you will not regret 3.54's and 35's. Although not a perfect comparison since I'm p-pumped, I see about 17 in town and 20+ on the highway. Usually run 70-ish which is well under 2k rpms

Andy505

Colorado Springs, CO

Captain Coop

I live part of the year in south Ga and Part in east Tn so id say im pretty rural. Is it necessary to replace the bearings?

Andy505

Not necessary, but a good idea. I was told by the local shop that sometimes bearings can get damaged when pressed off, unlikely but possible. So I just bought new ones and had them installed.

Captain Coop

The set that I was looking to buy on DTR is for a rear dana 60. Will they work for my front dana 60 or are they different somehow?

Andy505

I believe they are different, you are going to want the front dana 60.