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#1 |
Registered User
Join Date: Apr 2010
Location: Boise, ID
Posts: 1,280
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What is the best rear-end to run behind my 350?
What is the best rear end to run behind my 350 if I install a 700r4 and am looking for the best mileage out of my 68? Any input will be greatly appreciated. Thanks. I know nothing about the gear ratios.
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#2 |
Grandpa in the rustmobile...
Join Date: Nov 2008
Location: Spokane WA/Viola TN
Posts: 11,422
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Re: What is the best rear-end to run behind my 350?
373 seems like it'd be good with the OD trans
what motor/trans did your truck originally have?
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John Goose-1968 C10 355,9.32-1CR, Vortec Heads ,262 voodoo, 3.73:1 3OTT (HS ride/beater/farm truck) http://67-72chevytrucks.com/vboard/s...d.php?t=317684 Grams 53-1953 Chevrolet Belair http://67-72chevytrucks.com/vboard/s...=1#post4327784 1969 Chevy C10 Shortbed 4.5/6?" Frame off resto http://67-72chevytrucks.com/vboard/s...d.php?t=548136 1999 Toyota Tacoma 4x4 |
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#3 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Re: What is the best rear-end to run behind my 350?
you want to know the best gear, or the best rear end?
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#4 |
Rottenwood Garage Member
Join Date: May 2005
Location: Marietta, Georgia
Posts: 4,321
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Re: What is the best rear-end to run behind my 350?
Its going to depend on what you are doing with the truck.
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2004 Chevrolet Suburban C1500 2001 Chevrolet 2500HD Crew 6.0 1999 Harley Davidson Electra Glide 1972 Chevrolet C-20 Custom Camper "Dump Truck" 1972 Chevrolet C-20 Suburban "Big Green" 1969 Chevrolet C-50 Wedge Hauler "Leonidis" 1966 C-10 2x4 short fleet 327 4 speed "Race Truck" 1952 Plymouth Cranbrook "Rican" (my grandfathers) 1931 Ford Model A Coupe "Black Beauty" 1930 Ford Model A truck "Club Cab" 4x4 Rottenwood Garage and Speed Shop.....where everything must be racy! It's not just a hobby..It's a LIFESTYLE!!! Thanks for nothing Barrett-Jackson You cant fix stupid or teach accountability! Time wasters, looky Lous and tire kickers are everywhere! |
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#5 |
Registered User
Join Date: Oct 2007
Location: Valley Springs, Ca
Posts: 857
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Re: What is the best rear-end to run behind my 350?
![]() like me I have a 373 posi 12 bolt rear end and I get around 12 mpg with that if thats what you just want. and it will pull me just fine from 0-60 mph in around 5 seconds even in this heavy truck.
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![]() http://67-72chevytrucks.com/vboard/s...d.php?t=442487 My Picture Gallery http://67-72chevytrucks.com/gallery/...0&ppuser=36004 Last edited by Jeffs70; 02-28-2011 at 11:07 PM. |
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#6 |
Registered User
Join Date: Apr 2010
Location: Boise, ID
Posts: 1,280
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Re: What is the best rear-end to run behind my 350?
Forgive my lack of knowledge. It will be a daily driver, not much towing, I want limited slip with gearing that will get me the best mileage. Truck had I believe a 327 with a Powerglide. Powerglide still in it.
Last edited by ubtripn; 02-28-2011 at 11:16 PM. |
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#7 |
Hittin E-Z Street on Mud Tires
![]() Join Date: Nov 2004
Location: Greenville, SC
Posts: 23,090
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Re: What is the best rear-end to run behind my 350?
3.73
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Jesse James 1967 C10 SWB Stepside: 350/700R4/3.73 1965 Ford Mustang: 289/T5-5spd/3.25 Trac-Loc 1968 Pontiac Firebird: Project Fire Chicken! 2015 Silverado Double Cab 5.3L Z71 2001 Jeep Wrangler Sport 4.0L 5spd 2020 Chevrolet Equinox Premium 2.0L Turbo 2011 Mustang V6 ~ Wife's ride ![]() American Born, Country by the Grace of God ![]() 1967 CST Shop Truck Rebuild! My 1967 C-10 Build Thread My Vintage Air A/C Install Project "On a Dime" Trying my hand at Home Renovation! 1965 Mustang Modifications! |
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#8 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Re: What is the best rear-end to run behind my 350?
if you live in flat lands, then a 3.73 will probably be best. If in the mountains, maybe something a little steeper, 4.11 maybe. The overdrive will knock the RPMs down quite a bit.
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#9 |
Registered User
![]() Join Date: Sep 2003
Location: DFW
Posts: 765
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Re: What is the best rear-end to run behind my 350?
3.42
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#10 |
Registered User
Join Date: Dec 2008
Location: Ashland, KY
Posts: 700
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Re: What is the best rear-end to run behind my 350?
3.73s! had that setup in my 97 tahoe! it was amazing i really miss that truck bc it was great on the highway, great around town and great tugging and pulling
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68 C10 LWB 2/4 drop 406/th400/3.73posi 04 Silverado SS LQ9 6.0/4L65e/4.11posi AWD |
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#11 |
Registered User
Join Date: Jul 2007
Location: Toppenish, WA
Posts: 15,506
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Re: What is the best rear-end to run behind my 350?
Well, you would have to start with what you have now and go from there. Several of the guys will pipe in and say 4.11 gears but I'd go with 7.73 with the overdrive trans. That would let you cruise at highway speeds at a comfortable engine speed and still have a bit of zip off the line.
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#12 |
Happy to be here
![]() Join Date: Mar 2000
Location: Cypress, TX
Posts: 39,023
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Re: What is the best rear-end to run behind my 350?
Correct. Guys he is looking for MPG not best performance. With a 350 and 700r4, a 3.42 is the best overall gear. If you want a bit more torque, a 3.73 is good but it will cost you 1-2 MPG.
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#13 |
Registered User
Join Date: Dec 2009
Location: SoCAL
Posts: 121
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Re: What is the best rear-end to run behind my 350?
72/c10. I have a mild 350, and 700r4 tranny. stock rear with 3.73 Detroit Truetrac Diff. Daily driver for me. No regrets here..
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#14 |
Registered User
![]() Join Date: Sep 2003
Location: DFW
Posts: 765
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Re: What is the best rear-end to run behind my 350?
http://www.apexgarage.com/tech/gear_ratios.shtml
Using a 30" tall tire @ 2000RPM with stock 700r4 gearing and a final drive ratio of 3.42 you will have a cruise speed of 75MPH 1875 RPM at 70MPH w 3.42final |
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#15 |
Rottenwood Garage Member
Join Date: May 2005
Location: Marietta, Georgia
Posts: 4,321
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Re: What is the best rear-end to run behind my 350?
373 or the 342. If it was me I would try the 342 first.
I had an 89 throttle body set up in front of a 700R4 with 373's in my 1972 Suburban 2x4, 3/4 ton and averaged 12 in town and 15 on the highway. With a carb you wont do quite that good. Keep in mind you wont get "good" gas mileage...just better gas mileage!
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2004 Chevrolet Suburban C1500 2001 Chevrolet 2500HD Crew 6.0 1999 Harley Davidson Electra Glide 1972 Chevrolet C-20 Custom Camper "Dump Truck" 1972 Chevrolet C-20 Suburban "Big Green" 1969 Chevrolet C-50 Wedge Hauler "Leonidis" 1966 C-10 2x4 short fleet 327 4 speed "Race Truck" 1952 Plymouth Cranbrook "Rican" (my grandfathers) 1931 Ford Model A Coupe "Black Beauty" 1930 Ford Model A truck "Club Cab" 4x4 Rottenwood Garage and Speed Shop.....where everything must be racy! It's not just a hobby..It's a LIFESTYLE!!! Thanks for nothing Barrett-Jackson You cant fix stupid or teach accountability! Time wasters, looky Lous and tire kickers are everywhere! |
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#16 | |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Re: What is the best rear-end to run behind my 350?
And if there is any kind of a hill at all, the trans will be kicking back and forth from 3rd to 4th. 2100 RPM is where you want to keep it. 18xx will start to lug it and hurt MPG
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#17 |
Registered User
Join Date: Apr 2010
Location: Boise, ID
Posts: 1,280
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Re: What is the best rear-end to run behind my 350?
All I can say is WOW! and thank you. You all know so much that I don't have to learn things the hard way wasting money. Thanks again, for my application it sounds like 3.73. When you say final drive ratio does that mean the tranny and rear end combined? Are all of the automatic 700R4's geared the same inside? (Again, novice in gearing) BigBlue and Bajaracing - what kind of mileage do you get? What is your highway cruising speed? Thanks again for all of the info!
Someone on this board needs to start a thread - who and how did people build, work on and find parts for their trucks before the web and this message board? (Thanks for the correct on fuel mileage, it will be better, good is a judgment call.) Last edited by ubtripn; 03-01-2011 at 10:26 AM. |
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#18 |
Registered User
Join Date: Jun 2010
Location: Jefferson, MD
Posts: 2,397
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Re: What is the best rear-end to run behind my 350?
Yes, final drive technically is the rear axle ratio multiplied by the top transmission gear ratio. With a 3.42:1 rear end, your final drive is 2.394:1, given that a 700r4's top ratio is .70:1 .
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'68 Dodge Dart 270, 225, 904, 2.76--"Lucy" 1996 Gmc 1500 Z71, 350, 4l60e, 3.73s 1995 Jeep Wrangler Rio Grande 2.5, AX5, 4.10s 1989 Toyota Pickup 22re, auto, 3.73 |
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#19 |
Registered User
Join Date: Apr 2010
Location: Boise, ID
Posts: 1,280
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Re: What is the best rear-end to run behind my 350?
Man thanks, this is like being in school but listening.
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#20 |
It's Better With Nitro
Join Date: Apr 2008
Location: Chino Hills, CA
Posts: 2,261
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Re: What is the best rear-end to run behind my 350?
What's kind of missing in all of this is how tall (diameter) of a tire are you running or plan to run?
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1963 C-10: Deluxe-optioned cab, shortbed, fleetside Pontiac 462 ci, Kauffman D-Port alum. heads 4L80E, narrowed sheetmetal Ford 9-inch Tubular front and rear suspension Custom 6-piston front disc and 4-piston rear disc brakes Last edited by vin63; 03-01-2011 at 11:17 AM. |
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#21 |
Registered User
![]() Join Date: Sep 2003
Location: DFW
Posts: 765
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Re: What is the best rear-end to run behind my 350?
That's why I postulated a 30" tire the link in my previous post will calculate all you need to know and yeah you'll want to be up around 2100-2400 at cruise, below 2100 or so the converter may not have reached stall speed, causing increased trans fluid temps, lock up converter will help that but may hunt for lock up(lock in and out burning up the lock up in the converter)
Tire size will make a difference that is a variable you NEED to know to make an accurate choice Posted via Mobile Device |
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#22 |
the boat guy
Join Date: Jul 2007
Location: springfield mo
Posts: 2,339
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Re: What is the best rear-end to run behind my 350?
my 4l60e and 373 setup really likes a tall tire. I put some short tires on last year and hated them. I'd go 342 and fine tune w tire size.
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#23 |
Registered User
Join Date: Apr 2010
Location: Boise, ID
Posts: 1,280
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Re: What is the best rear-end to run behind my 350?
They will be a taller, I don't like the big rim, little rubber look much. 30 inches is close.
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#24 | |
Registered User
Join Date: Feb 2008
Location: sacramento california
Posts: 204
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Re: What is the best rear-end to run behind my 350?
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#25 |
Senior Member
![]() Join Date: Jun 2010
Location: Orlando, Florida
Posts: 2,508
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Re: What is the best rear-end to run behind my 350?
0 - 60 in 5 seconds? That seems a little optimistic.
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71 Chevy C10 Shortbed Stepside. LT1 with 4l60E. Just got back from painter, in assembly now. |
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