1971 K10 Rear Axle ? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**Ironhorse** · 01-17-2013, 10:57 AM

Doing a swap on my '71 K10, orginally sm465/np205. Going to a 350TH/np205 which has created some issuses of changing slip yokes and such. Nothing time and money hasn't been able to overcome. As I was under the truck I scraped and cleaned the rear axle housing and found the following:
TAY W 3642 stamped in the top right side of the rear housing. Can someone fill me in on the rest of the axle code? I have a Red Book that shows TAY as a 3.07:1 ratio. Running 31x10.50x15's on 8'' rally wheels. Being a 4x4 I would have thought it would have a taller gear such as a 3.73:1 or such. As far as I know the axles have never been changed, bought the truck in '84, was really beat. Again, nothing time and money hasn't been able to overcome.

Mike C · 01-17-2013, 01:26 PM

At least in a Blazer, the 350 got 3.07 gears standard with 3.73 first up option in '71-'72. Look on the FRONT axle for a tag that is bolted between two of the cover bolts on passenger side of pumpkin. It should have the ratio and ring & pinion tooth count stamped into it. Assuming a PO hasn't removed it... I wish GM had used ratio tags on their axles same as Dana did.

**Ironhorse** · 01-17-2013, 07:34 PM

I'll look for the tag you mentioned but doubt it is there, had this truck since
'84, been under many an hour and don't recall seeing a tag. Really don't think the gears have ever been changed since new.

70K10Hunter · 01-17-2013, 11:06 PM

my 70 K10 has 3.07s up front.haven't checked the back yet.

SS Tim · 01-18-2013, 07:21 AM

71 powertrain chart.

**Ironhorse** · 01-18-2013, 08:43 AM

Tim, thanks for posting that. You always have the info needed, what book or manual do you find your information in? Would be nice to have a copy if I could find one.

520CheyenneK10 · 11-09-2013, 07:34 PM

Hey I'm doing my front/rear diffs and both have open 3.07 gearing. Is this normal to have both the same. It has a th350 tranny and the first gen. NP205 case with conventional 4x4 (warn locking hubs) front axle is a dana 44 and rear is a corporate 12 bolt. my rigs a 1973 K10 Short wide

Bigdav160 · 11-09-2013, 07:43 PM

If they were not the same (or extremely close like 4.10 and 4.11) the vehicle would be locked up and wouldn't go anywhere.

520CheyenneK10 · 11-09-2013, 07:51 PM

Quote:

Originally Posted by Bigdav160

If they were not the same (or extremely close like 4.10 and 4.11) the vehicle would be locked up and wouldn't go anywhere.

Thanks for the explanation. Gears and ratios are not my strong points. Appreciate it

19silverado77 · 11-28-2013, 12:30 AM

Have you sold the sm465/205 setup.

**Ironhorse** · 11-28-2013, 08:37 AM

Sorry, had the transfer and tranny sold before I even had them pulled out.

01-17-2013, 10:57 AM	#1
Ironhorse Senior Member Join Date: Jul 2001 Location: Wellington, Ks Posts: 10,294	1971 K10 Rear Axle ? Doing a swap on my '71 K10, orginally sm465/np205. Going to a 350TH/np205 which has created some issuses of changing slip yokes and such. Nothing time and money hasn't been able to overcome. As I was under the truck I scraped and cleaned the rear axle housing and found the following: TAY W 3642 stamped in the top right side of the rear housing. Can someone fill me in on the rest of the axle code? I have a Red Book that shows TAY as a 3.07:1 ratio. Running 31x10.50x15's on 8'' rally wheels. Being a 4x4 I would have thought it would have a taller gear such as a 3.73:1 or such. As far as I know the axles have never been changed, bought the truck in '84, was really beat. Again, nothing time and money hasn't been able to overcome. __________________ 1971 Chevy 1/2T 4x4 LWB 350 V-8 Was sm465-now 350TH/np205 Tilt, Tach, Towhooks Original Truck AM/FM Wellington, Ks

01-17-2013, 01:26 PM	#2
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,728	Re: 1971 K10 Rear Axle ? At least in a Blazer, the 350 got 3.07 gears standard with 3.73 first up option in '71-'72. Look on the FRONT axle for a tag that is bolted between two of the cover bolts on passenger side of pumpkin. It should have the ratio and ring & pinion tooth count stamped into it. Assuming a PO hasn't removed it... I wish GM had used ratio tags on their axles same as Dana did. __________________ 44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax

01-17-2013, 07:34 PM	#3
Ironhorse Senior Member Join Date: Jul 2001 Location: Wellington, Ks Posts: 10,294	Re: 1971 K10 Rear Axle ? I'll look for the tag you mentioned but doubt it is there, had this truck since '84, been under many an hour and don't recall seeing a tag. Really don't think the gears have ever been changed since new. __________________ 1971 Chevy 1/2T 4x4 LWB 350 V-8 Was sm465-now 350TH/np205 Tilt, Tach, Towhooks Original Truck AM/FM Wellington, Ks

01-17-2013, 11:06 PM	#4
70K10Hunter Registered User Join Date: Jun 2012 Location: Hill Country Posts: 435	Re: 1971 K10 Rear Axle ? my 70 K10 has 3.07s up front.haven't checked the back yet.

01-18-2013, 07:21 AM	#5
SS Tim Registered User Join Date: Aug 2010 Location: Edwards, CA Posts: 7,503	Re: 1971 K10 Rear Axle ? 71 powertrain chart. Attached Images __________________ Thanks, Tim * VIN/Model Decoders * Power Team Charts (engine/transmission/gear ratio) * Post Your Pickup SPID Blazer SPID Suburban/Panel SPID * RTFM ... Read The Factory Manuals... download 'em here Highlanders Do you have a 1972 Plaid Pickup? Plaid Blazer ** Plaid Suburban

01-18-2013, 08:43 AM	#6
Ironhorse Senior Member Join Date: Jul 2001 Location: Wellington, Ks Posts: 10,294	Re: 1971 K10 Rear Axle ? Tim, thanks for posting that. You always have the info needed, what book or manual do you find your information in? Would be nice to have a copy if I could find one. __________________ 1971 Chevy 1/2T 4x4 LWB 350 V-8 Was sm465-now 350TH/np205 Tilt, Tach, Towhooks Original Truck AM/FM Wellington, Ks

11-09-2013, 07:34 PM	#7
520CheyenneK10 Registered User Join Date: Oct 2013 Location: AZ Desert Posts: 102	Re: 1971 K10 Rear Axle ? Hey I'm doing my front/rear diffs and both have open 3.07 gearing. Is this normal to have both the same. It has a th350 tranny and the first gen. NP205 case with conventional 4x4 (warn locking hubs) front axle is a dana 44 and rear is a corporate 12 bolt. my rigs a 1973 K10 Short wide

11-09-2013, 07:43 PM	#8
Bigdav160 Registered User Join Date: Apr 2011 Location: Klein Texas Posts: 3,852	Re: 1971 K10 Rear Axle ? If they were not the same (or extremely close like 4.10 and 4.11) the vehicle would be locked up and wouldn't go anywhere. __________________ My Classics: '72 K20 Suburban + '65 Dodge Town Wagon '72 Corvette Roadster +'67 Corvette Roadster '73 Z-28 Camaro '63 Ford SWB Uni Pickup '50 Ford Coupe

11-28-2013, 12:30 AM	#10
19silverado77 Registered User Join Date: Nov 2013 Location: Tucson, Arizona Posts: 167	Re: 1971 K10 Rear Axle ? Have you sold the sm465/205 setup.

11-28-2013, 08:37 AM	#11
Ironhorse Senior Member Join Date: Jul 2001 Location: Wellington, Ks Posts: 10,294	Re: 1971 K10 Rear Axle ? Sorry, had the transfer and tranny sold before I even had them pulled out. __________________ 1971 Chevy 1/2T 4x4 LWB 350 V-8 Was sm465-now 350TH/np205 Tilt, Tach, Towhooks Original Truck AM/FM Wellington, Ks



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