K-10 drivetrain ? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

gmtruck71 · 12-30-2002, 06:20 PM

My 71 K-10 has 3.07:1 gears. The rear has failed and I would like to replace with something higher such as 3.42 or 3.55. The rear is 12 bolt GM the front is Dana 44. Cannot find 3.54 or 3.55 for the rear, and cannot find 3.42 for the front. I can only find 3.73s or the 3.07s for both front and rear. Has anyone done this, and is there any later models that will fit under the chasis without any modifications. Does anyone have 3.73s front and rear complete housings with rear posi? Thanks for your time.

gmtruck71 · 01-01-2003, 08:45 PM

ttt

Mudder · 01-01-2003, 08:48 PM

The 3.73's would be good gears for you and are a lot more common.

O'l Buck · 01-02-2003, 12:37 AM

I'd much rather have the 3.73's than the 3.07's......my truck has 3.07's and I hate them. Why anyone would order a 4x4 with 3.07's is beyond me. I've been trying to tear them up for 4 years now and still haven't got a really good excuse to replace them yet other than the fact that I hate them.

too many · 01-02-2003, 02:18 AM

gmtruck71,
What height tire are you running? I currently have a "set" of 3:07s in my 4x4, but have a set of 3:73s with rear posi on the shelf for future use. (lucky find from a 71 Blazer) I am running a 31" tall tire and am also planning to put a 700 O.drive in it in the future.

You may want to check out the RPM range/tire dia before investing in any gears. ...probably not a lot of diff between 3.73s and 3.55s. GOOD LUCK!!

bouncytruck · 01-02-2003, 12:49 PM

I'm running 35" tires with 4.10s. My first Blazer had 35" tires with 3.73. It was ok, gas mileage was much better, but it had a little less off the line. If your running 35s or less, go with at least the 3.73s.

The Joker · 01-02-2003, 10:41 PM

I took some 3:54 out of a blazer once and put them in my 1/2 ton 4X4 once and did not like them. The 3:54's took more gas but I sure had a big top end crusin down the high way. So I went back to the 3:73. which is good for normal use.

12-30-2002, 06:20 PM	#1
gmtruck71 xwrench2003 Join Date: Jan 2002 Location: Louisville, Ky Posts: 112	K-10 drivetrain ? My 71 K-10 has 3.07:1 gears. The rear has failed and I would like to replace with something higher such as 3.42 or 3.55. The rear is 12 bolt GM the front is Dana 44. Cannot find 3.54 or 3.55 for the rear, and cannot find 3.42 for the front. I can only find 3.73s or the 3.07s for both front and rear. Has anyone done this, and is there any later models that will fit under the chasis without any modifications. Does anyone have 3.73s front and rear complete housings with rear posi? Thanks for your time. __________________ Marty Hall 1971 K-10 LWB Cheyenne (461\T-400) 93 S-10 Blazer (330,000 and still going) 86 SS Monte Carlo (40,000 miles) 85 Chevy Scottsdale 02 Jeep Liberty

01-01-2003, 08:45 PM	#2
gmtruck71 xwrench2003 Join Date: Jan 2002 Location: Louisville, Ky Posts: 112	ttt __________________ Marty Hall 1971 K-10 LWB Cheyenne (461\T-400) 93 S-10 Blazer (330,000 and still going) 86 SS Monte Carlo (40,000 miles) 85 Chevy Scottsdale 02 Jeep Liberty

01-02-2003, 12:37 AM	#4
O'l Buck Recovering Truck Driver Join Date: Mar 2002 Location: Orleans, NE USA Posts: 1,883	I'd much rather have the 3.73's than the 3.07's......my truck has 3.07's and I hate them. Why anyone would order a 4x4 with 3.07's is beyond me. I've been trying to tear them up for 4 years now and still haven't got a really good excuse to replace them yet other than the fact that I hate them. __________________ 67 K-20 350, SM465, Eaton rear, 4.56 no spin option 00 Dodge 2500 4x4, 24V cummins, 5 speed Chad South Central Nebraska

01-02-2003, 02:18 AM	#5
too many Registered User Join Date: Jul 2001 Location: nw IL Posts: 211	gmtruck71, What height tire are you running? I currently have a "set" of 3:07s in my 4x4, but have a set of 3:73s with rear posi on the shelf for future use. (lucky find from a 71 Blazer) I am running a 31" tall tire and am also planning to put a 700 O.drive in it in the future. You may want to check out the RPM range/tire dia before investing in any gears. ...probably not a lot of diff between 3.73s and 3.55s. GOOD LUCK!! __________________ "My wife says I cant have them all - I tell her I can try!"

01-02-2003, 12:49 PM	#6
bouncytruck SKINNY TIRES RULE! Join Date: Sep 2001 Location: Bothell, WA Posts: 11,049	I'm running 35" tires with 4.10s. My first Blazer had 35" tires with 3.73. It was ok, gas mileage was much better, but it had a little less off the line. If your running 35s or less, go with at least the 3.73s. __________________ bouncytruck 1972 K5 The Hauler 1994 K1500 Suburban The Daily2010 Kia Soul Wife's Ride2014 Fiat 500L

01-01-2003, 08:48 PM	#3
Mudder Registered User Join Date: Feb 2001 Location: East Central, MO Posts: 11,336	The 3.73's would be good gears for you and are a lot more common.

01-02-2003, 10:41 PM	#7
The Joker Registered User Join Date: Dec 2002 Location: north cheyenne Posts: 30	GMCTruck I took some 3:54 out of a blazer once and put them in my 1/2 ton 4X4 once and did not like them. The 3:54's took more gas but I sure had a big top end crusin down the high way. So I went back to the 3:73. which is good for normal use. __________________ The Joker



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