72, 307, standard what rear end ratio - The 1947 - Present Chevrolet & GMC Truck Message Board Network

peglegs · 03-02-2011, 09:54 PM

damn this is a tough seller to deal with. i have to drive 1 1/2 hrs to look at a 72, 1/2 t., 2wd, 307, 3 or 4 sp.? has a floor shifter so its a 4 sp. i cant take off the cover it'll make a mess & almost had an argument with her to walk out back and look at the glove box sticker she finally agreed when i asked her if she really did want to sell this or not geeze! it said "posi-traction rear axle J70" on the sticker. i looked in the faq & did a search but couldnt find anything definite & should be 3:42 or 3:73 i probably wont look at it if i cant find which ratio it is and will not buy it if ultimately cant take off the cover off.

can someone tell me what the J70 is? and if all looks good is it worth the $250 she's asking? thats not what ill offer but she might not budge
ty all again

redbaron69 · 03-02-2011, 10:41 PM

my guess a 373. i could be wrong, but dont think a 342 was offered till mid 70s maybe early 80s.

ChevyLvr4Life · 03-02-2011, 10:53 PM

I have a 70 1/2 ton 2wd with 307 and 3spd, and mine's 3.73. From what I've read that's the most common ratio with this combo, unless it was special ordered with a lower or higher ratio. Is there any way she would let you jack up the rear and rotate right rear wheel 2 turns and count the revolutions of the driveshaft? That usually gives you an approximate idea of what the ratio is. I know this works on an open diff, not sure if its the same on a posi. Just a thought. The $250 price sounds good to me

trevrolet65 · 03-02-2011, 11:00 PM

The rear axel I bought out of a 71 burb 307 was posi 3:73's. Not sure about the J70, the burb was missing the glove box lid.

oldblue1968chevy · 03-02-2011, 11:06 PM

373

**Joesjunk** · 03-02-2011, 11:11 PM

Yep, 373

**special-K** · 03-03-2011, 09:07 AM

The option is the posi,not the ratio. The standard ratio would be 3.73 and an optional ratio would be listed.
J70 is Brake Booster - Hydraulic

FlounderGDI · 03-03-2011, 09:34 AM

Just a little word of warning... Just because the SPID says it's a posi doesn't mean that it still is a posi... When mine came from the factory it had a posi but sometime between then and when I bought it the rear was swapped out for an open diff-ed rear... I suggest if you can jack up the rear and spin the tires to know for sure.

dan76 · 03-03-2011, 05:34 PM

Quote:

Originally Posted by peglegs

damn this is a tough seller to deal with. i have to drive 1 1/2 hrs to look at a 72, 1/2 t., 2wd, 307, 3 or 4 sp.? has a floor shifter so its a 4 sp.

No assurances it's a 4-speed. Many column 3-speeds were switched to a floor shifter.....most were not done well.

big_al_71 · 03-03-2011, 05:43 PM

My truck was a 307 three speed on the column and it had 373's when we rebuilt id and installed the auburn unit..

peglegs · 03-04-2011, 02:40 AM

thanks all but i got spooked & chickened out the owner would not allow the cover to be removed for inspection the truck was parked out back a few years ago for some unknown reason so i didnt trust the situation it was pay for it then take it, i dont know would you trust this ?

**special-K** · 03-04-2011, 07:26 AM

No,I wouldn't buy a part I wasn't allowed to inspect

03-02-2011, 09:54 PM	#1
peglegs Registered User Join Date: Jul 2009 Location: grants pass, oregon Posts: 390	72, 307, standard what rear end ratio damn this is a tough seller to deal with. i have to drive 1 1/2 hrs to look at a 72, 1/2 t., 2wd, 307, 3 or 4 sp.? has a floor shifter so its a 4 sp. i cant take off the cover it'll make a mess & almost had an argument with her to walk out back and look at the glove box sticker she finally agreed when i asked her if she really did want to sell this or not geeze! it said "posi-traction rear axle J70" on the sticker. i looked in the faq & did a search but couldnt find anything definite & should be 3:42 or 3:73 i probably wont look at it if i cant find which ratio it is and will not buy it if ultimately cant take off the cover off. can someone tell me what the J70 is? and if all looks good is it worth the $250 she's asking? thats not what ill offer but she might not budge ty all again __________________ 1990 chevy 4x4 with a 1940 IHC body

03-02-2011, 10:41 PM	#2
redbaron69 Registered User Join Date: Jan 2009 Location: marion nc Posts: 588	Re: 72, 307, standard what rear end ratio my guess a 373. i could be wrong, but dont think a 342 was offered till mid 70s maybe early 80s. __________________ 69 short fleet 350/350 "under construction" 70 short step 307/3 speed

03-02-2011, 10:53 PM	#3
ChevyLvr4Life Registered User Join Date: Aug 2010 Location: Martinsville, VA Posts: 150	Re: 72, 307, standard what rear end ratio I have a 70 1/2 ton 2wd with 307 and 3spd, and mine's 3.73. From what I've read that's the most common ratio with this combo, unless it was special ordered with a lower or higher ratio. Is there any way she would let you jack up the rear and rotate right rear wheel 2 turns and count the revolutions of the driveshaft? That usually gives you an approximate idea of what the ratio is. I know this works on an open diff, not sure if its the same on a posi. Just a thought. The $250 price sounds good to me __________________ 1970 Chevy C10 LWB 307 3OTT 3.73 gear

03-02-2011, 11:00 PM	#4
trevrolet65 Registered User Join Date: Nov 2010 Location: Venus Texas Posts: 217	Re: 72, 307, standard what rear end ratio The rear axel I bought out of a 71 burb 307 was posi 3:73's. Not sure about the J70, the burb was missing the glove box lid.

03-02-2011, 11:06 PM	#5
oldblue1968chevy Grandpa in the rustmobile... Join Date: Nov 2008 Location: Spokane WA/Viola TN Posts: 11,422	Re: 72, 307, standard what rear end ratio 373 __________________ 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

03-02-2011, 11:11 PM	#6
Joesjunk Senior Member Join Date: May 2001 Location: Independence MO. Posts: 7,700	Re: 72, 307, standard what rear end ratio Yep, 373 __________________ 72 3/4t Custom Deluxe 402/auto 66k Original paint 71 3/4t 4x4 Custom Deluxe 10k original miles Original paint 71 3/4t Cheyenne 402 70k original paint 72 3/4t 4x4 Custom deluxe 72 3/4t 4x4 Custom deluxe 91k original paint 72 Cheyenne/30 Dually 69 Camaro SS396 4-speed 13 GMC 2500HD Duramax I bought new 05 Jeep Wrangler "Willys Edition" 12k miles (I bought new) 85 3/4 ton 4x4 Scottsdale 33k miles original paint 86 1 ton 4x4 SRW Silverado 454 restored 80 1 ton 4x4 SRW Silverado 9,434 original miles!! original paint 95 GMC 1 ton dually 4x4 my dad bought new 95 GMC 3/4 ton 4x4, regular cab 454, 31k original miles 2002 2500HD 4x4 regular cab 6.0L 67k miles 2002 2500HD 4x4 regular cab 8.1L 28k miles 2003 GMC 2500HD 4x4 regular cab Diesel 93k miles 67-72 Parts for sale

03-03-2011, 09:07 AM	#7
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,852	Re: 72, 307, standard what rear end ratio The option is the posi,not the ratio. The standard ratio would be 3.73 and an optional ratio would be listed. J70 is Brake Booster - Hydraulic __________________ "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; 03-03-2011 at 09:47 AM.

03-03-2011, 09:34 AM	#8
FlounderGDI Registered User Join Date: Sep 2009 Location: Lafayette, Indiana Posts: 339	Re: 72, 307, standard what rear end ratio Just a little word of warning... Just because the SPID says it's a posi doesn't mean that it still is a posi... When mine came from the factory it had a posi but sometime between then and when I bought it the rear was swapped out for an open diff-ed rear... I suggest if you can jack up the rear and spin the tires to know for sure. __________________ 1969 CST/10 "GreenAndWhite" 1974 Nova (SOLD... End of an Era) 2000 Impala (RIP) 2008 Malibu Brand Loyal... I've never owned a Vehicle not made by Chevrolet.

03-03-2011, 05:43 PM	#10
big_al_71 Registered User Join Date: Jun 2008 Location: South Florida Posts: 11,375	Re: 72, 307, standard what rear end ratio My truck was a 307 three speed on the column and it had 373's when we rebuilt id and installed the auburn unit.. __________________ Get your facts first, and then you can distort them as much as you please!!!!!. Sylvester's build thread >>>http://67-72chevytrucks.com/vboard/s...ht=big+rebuild

03-04-2011, 02:40 AM	#11
peglegs Registered User Join Date: Jul 2009 Location: grants pass, oregon Posts: 390	Re: 72, 307, standard what rear end ratio thanks all but i got spooked & chickened out the owner would not allow the cover to be removed for inspection the truck was parked out back a few years ago for some unknown reason so i didnt trust the situation it was pay for it then take it, i dont know would you trust this ? __________________ 1990 chevy 4x4 with a 1940 IHC body

03-04-2011, 07:26 AM	#12
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,852	Re: 72, 307, standard what rear end ratio No,I wouldn't buy a part I wasn't allowed to inspect __________________ "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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