5/8 ton gear ratios? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

woodie70 · 06-07-2008, 01:27 PM

i was thinking about changing out my r&p to gain some drivability on the highway.... 70' 5/8 ton, 350, two bbl, 3 speed.... should be 3.73 from all my research... wondering if any of you have done this and have any suggestions.
was thinking 3.08 or 3.38.
i am in the process of building a 90 350 2 bolt now, all stock engine converted to carb.... if i do that and go 350 turbo for tranny would that warrant me choosing a certain ratio.. not building a hot rod, i just drive it every day for now. thanks chad

**special-K** · 06-07-2008, 05:13 PM

I`m not familiar with a 5/8t.Never heard of that.What axle do you have?You need to be sure about the exact ratio you have.What form of research did you do?The best research would be drain gear oil,pull cover and either count teeth of find the ratio stamped in the ring gear.You can go with any ratio with what you are doing.If you have a 1/2t/12-bo;t rear you can go with 3.08s.

woodie70 · 06-07-2008, 05:38 PM

Quote:

Originally Posted by special-K

I`m not familiar with a 5/8t.Never heard of that.What axle do you have?You need to be sure about the exact ratio you have.What form of research did you do?The best research would be drain gear oil,pull cover and either count teeth of find the ratio stamped in the ring gear.You can go with any ratio with what you are doing.If you have a 1/2t/12-bo;t rear you can go with 3.08s.

i will pull cover and look... and as far as research it is various sites and specs i've found on the net.... never heard of 5/8 ton? 3/4 ton suspension in a half ton, 6 lug wheels, stoarge box in the bed? i'll look at mine to be sure on gears, but running a 235/75/15 @ 65mph i'm turning 3k. would like to improve milage and be able to run at least 70- 75. thats why i was thinking 3.08

67_C-30 · 06-07-2008, 05:43 PM

Never heard of the 5/8 either, at least not in these models. I've heard the 73-78 Chevy Big 10's and GMC Heavy Halfs referred to as 5/8 tons, but I don't think they existed in 67-72's. To have 3/4 suspension, it would have to have 8 lugs, unless it just has heavier springs. All regular 67-70 half tons had 6 lugs.

**too much stuff** · 06-07-2008, 05:46 PM

A 1/2 ton would have the 6 lug wheels. If you went to a 3:08 gear, that would be your best bet. Also not aware of a 5/8 ton in these years.

67_C-30 · 06-07-2008, 05:54 PM

Maybe that part of the Ultra Rare Cor... - nah, I'm not going to say it!

woodie70 · 06-07-2008, 05:59 PM

Quote:

Originally Posted by 67_C-30

Never heard of the 5/8 either, at least not in these models. I've heard the 73-78 Chevy Big 10's and GMC Heavy Halfs referred to as 5/8 tons, but I don't think they existed in 67-72's. To have 3/4 suspension, it would have to have 8 lugs, unless it just has heavier springs. All regular 67-70 half tons had 6 lugs.

ok now i'm confused! your telling me all 67 c10's have 6 lug pattern?

Longhorn Man · 06-07-2008, 06:20 PM

every 60 - 70 1/2 ton GM truck (maybe even older) came stock with 6 lug wheels.
I've also never heard of 5/8 ton, nor seen anything in factory documentation.
A 1/2 ton with heavy springs, is still a half ton. The tool storage box on the side was an option in its self, not related to any packages at all.
Now, if it is a 1/2 ton with a 3speed tranny, then it would in fact have the 3.73 gearing unles opted otherwise.
A 3.08 IMO is a great gear. Gives you the freeway RPMs just a tick higher than an overdrive, and take off isn't nearly as bad as some would make you believe.

woodie70 · 06-07-2008, 06:42 PM

Quote:

Originally Posted by Longhorn Man

every 60 - 70 1/2 ton GM truck (maybe even older) came stock with 6 lug wheels.
I've also never heard of 5/8 ton, nor seen anything in factory documentation.
A 1/2 ton with heavy springs, is still a half ton. The tool storage box on the side was an option in its self, not related to any packages at all.
Now, if it is a 1/2 ton with a 3speed tranny, then it would in fact have the 3.73 gearing unles opted otherwise.
A 3.08 IMO is a great gear. Gives you the freeway RPMs just a tick higher than an overdrive, and take off isn't nearly as bad as some would make you believe.

thanks on the 3.08 notes, thats what i was looking for. and i apologise for the 5/8 ton, i was mis informed. the truck is older than i am, but i'm getting there. thanks for the info, sorry for my ignorance

Longhorn Man · 06-07-2008, 06:53 PM

no big deal. Sometimes someone joins with info we've never heard of, and it's real. But more likely, some one has been misinformed. Thats what this place is all about, learning. (on a lesser forrum you woulda been called an idiot, but we won't do that here... not till we get to know you!)

woodie70 · 06-07-2008, 06:59 PM

that's geat! i am an idiot thought, so i'll save u guys the trouble of figurin it out.
no thanks haven't had it long itchin to start on it... fundage is my biggest issue.
i also blew the head gasketon my amc 360 muddin... that's my first priority.
thinkin ahead.

Pl4yboy · 06-07-2008, 07:43 PM

He's talking about the heavy half tons. My 69 camper special is like that.

**special-K** · 06-07-2008, 08:29 PM

Yeah,I would never raz a guy for being misinformed.FYI,GM just never had such a designation.Even the later Heavy Halfs and Big Tens were still...cough cough...halfs and tens...sniff sniff.

caminokid · 06-07-2008, 08:37 PM

Quote:

Originally Posted by Longhorn Man

every 60 - 70 1/2 ton GM truck (maybe even older) came stock with 6 lug wheels.
I've also never heard of 5/8 ton, nor seen anything in factory documentation.
A 1/2 ton with heavy springs, is still a half ton. The tool storage box on the side was an option in its self, not related to any packages at all.
Now, if it is a 1/2 ton with a 3speed tranny, then it would in fact have the 3.73 gearing unles opted otherwise.
A 3.08 IMO is a great gear. Gives you the freeway RPMs just a tick higher than an overdrive, and take off isn't nearly as bad as some would make you believe.

My 46 and 50 had 6 lugs with 16 inch wheels.

Longhorn Man · 06-07-2008, 10:09 PM

Quote:

Originally Posted by Pl4yboy

He's talking about the heavy half tons. My 69 camper special is like that.

You can call it that... But... GM never did.

Quote:

Originally Posted by caminokid

My 46 and 50 had 6 lugs with 16 inch wheels.

Sweet.. more info!

67_C-30 · 06-07-2008, 11:59 PM

Quote:

Originally Posted by woodie70

that's geat! i am an idiot thought, so i'll save u guys the trouble of figurin it out.

You're working a '70 Chevy, so that makes you OK in my book. BTW, we love pics here, so cough 'em up!!

06-07-2008, 01:27 PM	#1
woodie70 Registered User Join Date: May 2008 Location: claremore,ok Posts: 14	5/8 ton gear ratios? i was thinking about changing out my r&p to gain some drivability on the highway.... 70' 5/8 ton, 350, two bbl, 3 speed.... should be 3.73 from all my research... wondering if any of you have done this and have any suggestions. was thinking 3.08 or 3.38. i am in the process of building a 90 350 2 bolt now, all stock engine converted to carb.... if i do that and go 350 turbo for tranny would that warrant me choosing a certain ratio.. not building a hot rod, i just drive it every day for now. thanks chad __________________ 1970 c10,150k original... drivin, yet project 1982 jeep cj 7, amc 360,9" lift,35x15.5 swampers 2005 nissan xterra 4x4,old ladies.

06-07-2008, 05:13 PM	#2
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,851	Re: 5/8 ton gear ratios? I`m not familiar with a 5/8t.Never heard of that.What axle do you have?You need to be sure about the exact ratio you have.What form of research did you do?The best research would be drain gear oil,pull cover and either count teeth of find the ratio stamped in the ring gear.You can go with any ratio with what you are doing.If you have a 1/2t/12-bo;t rear you can go with 3.08s. __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~

06-07-2008, 05:43 PM	#4
67_C-30 I have a radical idea! Join Date: Jan 2005 Location: Sweet Home Alabama! Posts: 6,513	Re: 5/8 ton gear ratios? Never heard of the 5/8 either, at least not in these models. I've heard the 73-78 Chevy Big 10's and GMC Heavy Halfs referred to as 5/8 tons, but I don't think they existed in 67-72's. To have 3/4 suspension, it would have to have 8 lugs, unless it just has heavier springs. All regular 67-70 half tons had 6 lugs. __________________ '67 C-30 Dually Pickup 6.2 Turbo Diesel, NP435 ‘72 C-10 SWB , 350 4bbl, TH350 '69 C-10 SWB , 250 L6, 3 OTT '69 GMC C3500, dump truck, 351 V6, NP435 '84 M1009 CUCV Military Blazer 67 C-30 Turbodiesel build thread http://67-72chevytrucks.com/vboard/s...d.php?t=254096 My trucks http://s226.photobucket.com/albums/d...ediafilter=all Member of the 1-Ton Club! Last edited by 67_C-30; 06-07-2008 at 05:44 PM.

06-07-2008, 05:46 PM	#5
too much stuff Roadtrip! Join Date: Feb 2003 Location: Grand Rapids MN Posts: 13,787	Re: 5/8 ton gear ratios? A 1/2 ton would have the 6 lug wheels. If you went to a 3:08 gear, that would be your best bet. Also not aware of a 5/8 ton in these years. __________________ 67 gmc custom lwb dakota truck. Sold...And bought back 69 swb 4x4 project (in progress) 70 c-10 lwb texas truck 70 4x4/BB/bkts/posi/tach(retired) 70 swb (wifes) 70 jimmy camper 71 K-5 factory 2wd 71 cheyenne 4x4/tach/posi/ plow rig 71 Cheyenne20 BB, buckets, tach, tilt, 4 speed 72 jimmy CST wyoming rig 72 jimmy Colorado rig 72 lifted texas 4x4 3/4 ton burb 65 fury conv. 383/auto 65 chrysler 300 "L" 413 auto

06-07-2008, 05:54 PM	#6
67_C-30 I have a radical idea! Join Date: Jan 2005 Location: Sweet Home Alabama! Posts: 6,513	Re: 5/8 ton gear ratios? Maybe that part of the Ultra Rare Cor... - nah, I'm not going to say it! __________________ '67 C-30 Dually Pickup 6.2 Turbo Diesel, NP435 ‘72 C-10 SWB , 350 4bbl, TH350 '69 C-10 SWB , 250 L6, 3 OTT '69 GMC C3500, dump truck, 351 V6, NP435 '84 M1009 CUCV Military Blazer 67 C-30 Turbodiesel build thread http://67-72chevytrucks.com/vboard/s...d.php?t=254096 My trucks http://s226.photobucket.com/albums/d...ediafilter=all Member of the 1-Ton Club!

06-07-2008, 06:20 PM	#8
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Re: 5/8 ton gear ratios? every 60 - 70 1/2 ton GM truck (maybe even older) came stock with 6 lug wheels. I've also never heard of 5/8 ton, nor seen anything in factory documentation. A 1/2 ton with heavy springs, is still a half ton. The tool storage box on the side was an option in its self, not related to any packages at all. Now, if it is a 1/2 ton with a 3speed tranny, then it would in fact have the 3.73 gearing unles opted otherwise. A 3.08 IMO is a great gear. Gives you the freeway RPMs just a tick higher than an overdrive, and take off isn't nearly as bad as some would make you believe.

06-07-2008, 06:53 PM	#10
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Re: 5/8 ton gear ratios? no big deal. Sometimes someone joins with info we've never heard of, and it's real. But more likely, some one has been misinformed. Thats what this place is all about, learning. (on a lesser forrum you woulda been called an idiot, but we won't do that here... not till we get to know you!)

06-07-2008, 06:59 PM	#11
woodie70 Registered User Join Date: May 2008 Location: claremore,ok Posts: 14	Re: 5/8 ton gear ratios? that's geat! i am an idiot thought, so i'll save u guys the trouble of figurin it out. no thanks haven't had it long itchin to start on it... fundage is my biggest issue. i also blew the head gasketon my amc 360 muddin... that's my first priority. thinkin ahead. __________________ 1970 c10,150k original... drivin, yet project 1982 jeep cj 7, amc 360,9" lift,35x15.5 swampers 2005 nissan xterra 4x4,old ladies.

06-07-2008, 07:43 PM	#12
Pl4yboy Freeeeee Mason... Join Date: Sep 2006 Location: McAlester, Oklahoma Posts: 320	Re: 5/8 ton gear ratios? He's talking about the heavy half tons. My 69 camper special is like that. __________________ Daily Driver -2007 Chevy -Dark Blue Metallic -Regular Cab -4.8 V8 -4x4 Ongoing, Never Ending, PITA, Love of my Life -69 Chevy C/10, Camper Special -350/TH400 -Loudest System on the Board

06-07-2008, 08:29 PM	#13
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,851	Re: 5/8 ton gear ratios? Yeah,I would never raz a guy for being misinformed.FYI,GM just never had such a designation.Even the later Heavy Halfs and Big Tens were still...cough cough...halfs and tens...sniff sniff. __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~

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