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#1 |
Registered User
Join Date: Feb 2007
Location: Texas
Posts: 4
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Need HELP !!! 1970 GMC 3/4 .
I am new to all this so please be gentle with me.
I just bought a 1970 3/4 ton GMC truck and am triing to get all the information I can about it. So could someone please direct me to a webpage that I can get information about the truck and especially a Dana 60 differential. I know I have a small block 350 and a Turbo 350 Transmission but I don't know about the rear end. I am interested in see what gearing is in it. PLeas someone Help !!!!!! |
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#2 |
Designated A-hole!
Join Date: Mar 2003
Location: South Mississippi
Posts: 36,450
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Re: Need HELP !!! 1970 GMC 3/4 .
Welcome to the board from South Mississippi! You're at the only place you'll need for info. The best way to find the ratio is to pull the rear cover and look.
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"If it ain't broke, fix it 'til it is!" Being stupid ain't illegal. ![]() We're Still Debt Free Except for the House!!! www.daveramsey.com 70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e 93 S-10 "Poppaw's Truck" |
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#3 |
Registered User
Join Date: Apr 2006
Location: oklahoma
Posts: 10,670
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Re: Need HELP !!! 1970 GMC 3/4 .
Welcome to the board from oklahoma. You are in the right place for the questions. Pull the cover to get the gear ratio. Since you just bought it it is a good time for preventavie maintance. So you might as well change the gear oil and you can find the ratio at the same time. Count the ring gear teeth and divide it by the pinion gear teeth count and you get your ratio. Then put a new gasket on the cover, reinstall and add fresh gear oil. Get 2 things done quickly. Hope this helps.
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#4 |
Senior Member
![]() Join Date: Dec 2006
Location: Studio City, Calif.
Posts: 2,873
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Re: Need HELP !!! 1970 GMC 3/4 .
I agree completely with the above 2 replies (And welcome from so. calif.) but I wanted to add that on my '69 GMC with Dana 60 there is a small metal tag on one of the lower bolts with the # of teeth and resultant gear ratio.
Or you can just jack up one side and turn the wheel one rev.exactly with the tranny in Neutral and count the drive-shaft revolutions exactly and multiply by 2.(unless of course you have traction control,then jack both wheels and don't multiply).
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'69 GMC C2500 Custom Camper, 8 1/2' bed, New GM 350, NP 435 Close Ratio 4spd. Trans., 3.73 Dana-60 open.Camper and Trailer wiring, PS, PB, AC, tach , three gas tanks, stereo speakers, 2nd owner, Work-Truck supreme. |
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#5 |
King of Rust
Join Date: Jul 2005
Location: St Petersburg, FL
Posts: 359
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Re: Need HELP !!! 1970 GMC 3/4 .
Welcome, nice to see another 70 GMC 3/4. My tag was broken but there was once one there.
Here is my glove box options list, to give you an idea of what the 70's came with; ![]() Post some pics!! Last edited by KAILUAZ; 02-11-2007 at 02:35 PM. |
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#6 |
In Memoriam...
Join Date: Nov 2006
Location: Wallburg, NC
Posts: 1,216
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Re: Need HELP !!! 1970 GMC 3/4 .
Hello firedawg99...A big HOWDY from Wallburg, NC.
I agree with all the others above, this is THE place to get the info you need. Just ask away. ![]()
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'68 C10 SWB 307ci 2BBL FarmTruk Pics Here "You know, doing what is right is easy. The problem is knowing what is right." |
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#7 |
Account Suspended
Join Date: Mar 2003
Location: ** THE FALL GUY **CHICAGO IL
Posts: 5,883
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Re: Need HELP !!! 1970 GMC 3/4 .
welcome from chigaco
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#8 |
Special Order
![]() ![]() Join Date: Nov 2004
Location: Mt Airy, MD
Posts: 85,858
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Re: Need HELP !!! 1970 GMC 3/4 .
For a quick check on the ratio:mark the tire and the driveshaft yoke with reference marks as mentioned.Spin the tire one full turn while counting the revolutions of the driveshaft.If it`s a 4.10,it`ll turn a bit past the mark after 4 spins.If it spins about 3 3/4 turns,it`s a 3.73.Around 4 1/2,it`s a 4.56,etc.
I don`t know why you`d want to multiply by 2.I`ve never heard that and can`t see a reason.There are only so many ratios and they basically run shy of a 1/2 turn apart with the spread increasing as the numbers go higher:3.73,4.10,4.56.So,that`s as accurate as you need.
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"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 ~ Last edited by special-K; 02-11-2007 at 07:24 PM. |
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#9 | |
Senior Member
![]() Join Date: Dec 2006
Location: Studio City, Calif.
Posts: 2,873
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Re: Need HELP !!! 1970 GMC 3/4 .
Quote:
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'69 GMC C2500 Custom Camper, 8 1/2' bed, New GM 350, NP 435 Close Ratio 4spd. Trans., 3.73 Dana-60 open.Camper and Trailer wiring, PS, PB, AC, tach , three gas tanks, stereo speakers, 2nd owner, Work-Truck supreme. |
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#10 |
Registered User
Join Date: Feb 2007
Location: Texas
Posts: 4
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Re: Need HELP !!! 1970 GMC 3/4 .
Thanks to all that responded. I am just getting started on it and all this is very new.
Have you ever heard of a aftermarket factory a/c under the dash. I might need a replacement unit later on. Thanks again for the warm welcome |
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#11 |
To The Levy
Join Date: Jan 2007
Location: california
Posts: 391
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Re: Need HELP !!! 1970 GMC 3/4 .
welcome to sight, yes drop cover count teeth on both gears and dived the two, fill with fresh new clean fluid, silicone works too inplace of gasket.
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#12 |
Senior Member
![]() Join Date: Dec 2006
Location: Studio City, Calif.
Posts: 2,873
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Re: Need HELP !!! 1970 GMC 3/4 .
Let's see some more pics too. With the 4spd CR and G70 springs I'll bet it saw camper duty or maybe trailering.
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'69 GMC C2500 Custom Camper, 8 1/2' bed, New GM 350, NP 435 Close Ratio 4spd. Trans., 3.73 Dana-60 open.Camper and Trailer wiring, PS, PB, AC, tach , three gas tanks, stereo speakers, 2nd owner, Work-Truck supreme. |
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#13 | |
King of Rust
Join Date: Jul 2005
Location: St Petersburg, FL
Posts: 359
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Re: Need HELP !!! 1970 GMC 3/4 .
Quote:
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#14 |
Registered User
Join Date: Oct 2006
Location: Oakridge Oregon
Posts: 1,865
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Re: Need HELP !!! 1970 GMC 3/4 .
Welcome to the board from Oregon........ Nice start for a truck!
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68 CST SWB - Gold/White 50th anniversary /TH350/Buddy Buckets/3.73 Posi/dogdish caps. 68 K10 Burb - Gold/White 327/SM465/NP205/3.73 "Daa Burb" build thread |
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#15 |
Registered User
Join Date: Apr 2006
Location: oklahoma
Posts: 10,670
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Re: Need HELP !!! 1970 GMC 3/4 .
Do you mean you already have an aftermarket a/c in it or are you asking about putting a vintage air or old air type retrofit unit? I have seen the under dash aftermarket a/c. Took one off of a 68 chevy a few years back. Does it stick out below the stock heater? If so then it is probably a old knee knocker a/c system. Pics would help.
Last edited by Aarons72s; 02-14-2007 at 04:27 PM. |
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#16 |
Registered User
Join Date: Mar 2006
Location: USA
Posts: 21,020
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Re: Need HELP !!! 1970 GMC 3/4 .
No need to count the teeth.Look for the numbers in the last column.Match them to some numbers you will find on the ring gear,and then you can find out what gear ratio it is this way.
Ratio 2.56:1 - Tooth Combination 41,16 Ratio 2.73:1 - Tooth Combination 41,15 Ratio 3.07:1 - Tooth Combination 43,14 Ratio 3.08:1 - Tooth Combination 40,13 Ratio 3.08:1 - Tooth Combination 37,12 Ratio 3.31:1 - Tooth Combination 43,13 Ratio 3.36:1 - Tooth Combination 37,11 Ratio 3.42:1 - Tooth Combination 41,12 Ratio 3.55:1 - Tooth Combination 39,11 Ratio 3.73:1 - Tooth Combination 41,11 Ratio 4.10:1 - Tooth Combination 41,10 Ratio 4.11:1 - Tooth Combination 37,9 Last edited by 1969k10stepside; 02-14-2007 at 04:30 PM. |
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#17 | |
Senior Member
![]() Join Date: Dec 2006
Location: Studio City, Calif.
Posts: 2,873
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Re: Need HELP !!! 1970 GMC 3/4 .
Quote:
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__________________
'69 GMC C2500 Custom Camper, 8 1/2' bed, New GM 350, NP 435 Close Ratio 4spd. Trans., 3.73 Dana-60 open.Camper and Trailer wiring, PS, PB, AC, tach , three gas tanks, stereo speakers, 2nd owner, Work-Truck supreme. |
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#18 |
GMCDAC
Join Date: Apr 2006
Location: Rapid City, SD
Posts: 837
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Re: Need HELP !!! 1970 GMC 3/4 .
Hey Firedawg and all, cool to see the 3/4 GMC's guys. Nice trucks!! My 72 is a 4:10 according to the diff. tag. Never bothered to actually count the teeth when the cover has been off.
A bigger pic would be cool too! Later---DAC
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1970 GMC K5 Jimmy Custom 4X4 Mom's driver from 1971 to 2001!! Under rebuild! 1972 GMC C2500 Pickup owned since 1979 Needs a rest and refurbish! 1955 GMC 100 2nd design driven almost daily! Rest In Peace Mom. "Dolly" 7/15/23 - 5/18/09 GMC driver for 30 years! ![]() |
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