410 Or 456?

[BIGCHEVY4X]

i i have a 6.5 diesel with a th400 and a 205 tcase and right now its got 373s but im going to run 37MTRs and i cant decide between the 410s and 456s. I want more power but id also like to run 8omph on the freeway. I looked at 4los gear chart and it looks like 410s with 37s wouldent have much power. What do you guys think?

 

[blowedupmotor87]

I'm planning on running 4:56 gears with 37's 350/465/203/205/60/14. I kinda would rather have 4.88 but, 4.56 is what I have so...Anyways, seems to me 4.56 would be a good choice! Plus, they come stock in CUCV axles (why I have them).

 

[Mudstud]

you won't feel much of a dif if you only go from 3.73 to 4.10. Without a doubt go at least 4.56. Infact is you aren't too conserned with milage I'd suggest 5.13. I have 36" tires and 5.13s The power is there and it even has a bit of compression braking from a stock th350. I can run about 70 in the interstate. . . when death wobble isn't presenting itself.

 

[Hogback Fabrication]

You won't be able to run 80 mph with 4.56's and the diesel.

If you are going to run 80 either keep the gears you have or get a trans with an overdrive.

 

[zero cool]

Use my gear ratio calculator and you can see a side-by-side comparison of the two. You can even adjust the speeds to see how they will run at 80. http://www.grimmjeeper.com/gears.html

 

[cbbr]

I am going from 4.10 to 4.56. The 37's are a little tall for 4.10's IMO.

 

[Hogback Fabrication]

I am going from 4.10 to 4.56. The 37's are a little tall for 4.10's IMO.

I thought 4.56 were too deep when I had 37's.

80 mph with 4.56 gears is 3500-3600 RPM, probably past the redline of the 6.5 (and you probably be getting 5 mpg anyway)

80 mph with 3.73 gears is 2800-2900. I wouldn't regear at all.

 

[mudman83]

The redline for a 6.2 is ~3800, but it will be really loud running at 3500 rpm to go 80. It also can't be good for it.

 

[cbbr]

I don't drive 80 mph and have a 350/th400.

 

[Hogback Fabrication]

I don't drive 80 mph and have a 350/th400.

Last I checked this wasn't your thread

 

[cbbr]

Ya got me there, just clarifying. And .

 

[BIGCHEVY4X]

with the 373s in it now it will get to 80 eventually but thats seems very unrealistic with the 456s I wouldent drive it much over 3500...i tired putting some info into that caculator and i think im going to with the 410s for now just beacuse they are easier for me to get to......

 

[86dieselburb]

I've got a 6.2 Burb with TH400 and 4.10's on 36 tires and it is one gutless pig. I cannot imagine with 3.73's. I would say go to 4.10's. You will be a lot happier. Cruising at 70mph is no problem and I think I've even had it up to 90, down hill. At 80mph, your gas mileage is gonna blow chunks though.
Even at 70 mileage sucks. 60-65 seems bout right for mileage with 4.10's. I wouldn't go any lower with the gears unless you have an over drive.