4.10s or 4.56s for my pretty much stock K5?

[WantedaDodge]

I'm rebuilding the 700R4 in my '84 K5. It's a stock 350, soon to be supplemented with headers, 3.5 inch exhaust and a 2.5 inch lift with 33 inch tires.

I'm just going to regear the 10 bolts cause they will be plenty strong for as hard as I'm going to run it(it's for hunting, badweather driving, the dunes, an ocassional mudding session and amateur trails). My buddies and I have ran plenty of Dana 44s, 10 and 12 bolts hard in this same manner and have never had problems. I don't want to go through the headache of 8 bolt wheels cause I simply don't need that kind of strength.

If they made 4.30s for 10 bolts, thats what I would go for, but they don't! Since I'm going to regear, the obvious choice was 4.10s, but I got to thinking about maybe going to 4.56s since I have the overdrive.
What do you all think? The motor will at the most someday have 300 horsepower, but not likely. Probably closer to 250-275...

I just want something reliable that isn't likely to get stuck and will climb snotty hills and logging roads.

 

[rick88blaze]

I have 4.56's in mine with 33's and love it. With the overdrive I can still cruise down the interstate at 70 to 80 MPH with no problem. At about 75 I am running about 2500 rpm's.

Rick

 

[WantedaDodge]

Thats what I wanted to hear!! I was hoping it would run about 2500 at 75, those were my 'guesstimates'

Did you swap them out from something else? What did you have before?

 

[rick88blaze]

I swapped in the 12 bolt and Dana 44 in Dec' 03. My K5 had the factory 10 bolts front and rear with 3.42's when I bought it. My carrier bearings went out of my rear 10 bolt in Nov '03 and I got one hell of a deal on my 12 bolt and 44. I bought them out of a totalled '76 K10. The guy just had them both rebuilt with new gears and the locker about 6 months before he totalled the truck out. His receipt said $2300 on it and I got them for $400. Hell, both of them still had the paint markings on the ring gears when I changed the fluid before I installed them.

Rick

 

[hunterguy86]

hey sorry to hi jack but what did the 4.56s do to your gas mileage? im thinkin of doin the swap but i daily drive the blazer still.

 

[rick88blaze]

They didn't really effect it at all. If anything, they made it better since it brought my engine back up to the powerband.

Rick

 

[mrk5]

hey sorry to hi jack but what did the 4.56s do to your gas mileage? im thinkin of doin the swap but i daily drive the blazer still.

I drove out to Moab with 3.73 gears, and drove back with 4.56 gears (you can see the story here). I got the same gas mileage both directions. I'm lovin' the lower gears.