Can i use 3.08 insted of 3.73??? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

mx jim · 04-06-2003, 06:06 PM

I have a 12 bolt rear end with 3.73 gears, out of a 1970 chevy short bed. I was woundering if i could use my rear end but put 3.08 gears in it? Or am i going to have to get a new rear end. Thanks jim. Bye the way i am 17 years old and this is my first truck.

mikep · 04-06-2003, 06:28 PM

You'd be better off finding someone who would trade their rear end for yours . Otherwise the gears and setup would put you around $500+ . I'm sure there are a lot of folks on this board who would be happy to do that if they live close to you.

bpmcgee · 04-06-2003, 07:15 PM

I learned the hard way that when you swap from 3.73's down to 3.08s you need a different carrier.

Brian

mx jim · 04-06-2003, 07:20 PM

What is carrier??

crazy longhorn · 04-06-2003, 08:04 PM

the carrier is what the ring gear is bolted to(also houses the spider gears). The 3.08 is on a 3 series carrier, & the 3.73 & lower are on a 4 series carrier. I agree with MikeP, it would be much cheaper to swap complete rear diffs with someone, rather than set up gears & replace the carrier. Good luck,crazyL

chevy2racr · 04-06-2003, 11:59 PM

bpmcgee, sounds like a destroyed ring and pinion set?? my pinion seal went out tosay on my way home from town. I guess its time to get the 3.08 posi ready and get new u-bolts and get a speedo gear too :-)

Ed ke6bnl · 04-07-2003, 07:52 AM

Quote:

Originally posted by mx jim
I have a 12 bolt rear end with 3.73 gears, out of a 1970 chevy short bed. I was woundering if i could use my rear end but put 3.08 gears in it? Or am i going to have to get a new rear end. Thanks jim. Bye the way i am 17 years old and this is my first truck.

presently we have two rear ends one is in the 70 chevy with a noisy 3.73 5 lug that we want to put 3.08'sin The other rearend is a 3.08 was told from a 70 ish pu with 6 lug and posi. can the center section from the 3.08 be moved to the 3.73. Thanks Ed ke6bnl So.Calif.

crazy longhorn · 04-07-2003, 08:09 AM

I would check the width flange to flange on the axles......if the spare diff is a 70, the 5 lug axles should swap in. The 67-69 diffs are 1 1/2" narrower. If you have the older diff, yes you can swap the 3.08 ring /pinion & carrier into your diff. You just need to check backlash before tearing the 3.08 diff down, & use the pinion shim with the 3.08 gears. After you are all set up , run the pattern with marking compound to be sure the pinion depth/backlash is correct. good luck,crazyL

04-06-2003, 06:06 PM	#1
mx jim Registered User Join Date: Mar 2002 Location: agua dulce CA USA Posts: 35	Can i use 3.08 insted of 3.73??? I have a 12 bolt rear end with 3.73 gears, out of a 1970 chevy short bed. I was woundering if i could use my rear end but put 3.08 gears in it? Or am i going to have to get a new rear end. Thanks jim. Bye the way i am 17 years old and this is my first truck. __________________ mxjim 1970 chevy 4x4, 400 small block, 4" pro comp lift, with 35s.

04-06-2003, 06:28 PM	#2
mikep Used to have a truck Join Date: May 2002 Location: port orchard WA Posts: 1,552	You'd be better off finding someone who would trade their rear end for yours . Otherwise the gears and setup would put you around $500+ . I'm sure there are a lot of folks on this board who would be happy to do that if they live close to you. __________________ No truck :-(

04-06-2003, 07:20 PM	#4
mx jim Registered User Join Date: Mar 2002 Location: agua dulce CA USA Posts: 35	What is carrier?? __________________ mxjim 1970 chevy 4x4, 400 small block, 4" pro comp lift, with 35s.

04-06-2003, 08:04 PM	#5
crazy longhorn Fabricate till you "puke" Join Date: Jun 2002 Location: Ill Posts: 9,402	the carrier is what the ring gear is bolted to(also houses the spider gears). The 3.08 is on a 3 series carrier, & the 3.73 & lower are on a 4 series carrier. I agree with MikeP, it would be much cheaper to swap complete rear diffs with someone, rather than set up gears & replace the carrier. Good luck,crazyL __________________ 69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears....

04-06-2003, 11:59 PM	#6
chevy2racr So Many Ideas, So Little Money Join Date: Sep 2001 Location: Marshalltown, IA Posts: 1,610	bpmcgee, sounds like a destroyed ring and pinion set?? my pinion seal went out tosay on my way home from town. I guess its time to get the 3.08 posi ready and get new u-bolts and get a speedo gear too :-) __________________ 72 Blazer 3/4 ton running gear 4.10s NP205/TH350 350 4in lift half doors 71 C10 with 454 99 S-10 5.1L SBC 700R4 09 Malibu Marshalltown, Iowa

04-06-2003, 07:15 PM	#3
bpmcgee Registered User Join Date: Mar 2003 Location: Northern Illinois Posts: 2,181	I learned the hard way that when you swap from 3.73's down to 3.08s you need a different carrier. Brian

04-07-2003, 08:09 AM	#8
crazy longhorn Fabricate till you "puke" Join Date: Jun 2002 Location: Ill Posts: 9,402	I would check the width flange to flange on the axles......if the spare diff is a 70, the 5 lug axles should swap in. The 67-69 diffs are 1 1/2" narrower. If you have the older diff, yes you can swap the 3.08 ring /pinion & carrier into your diff. You just need to check backlash before tearing the 3.08 diff down, & use the pinion shim with the 3.08 gears. After you are all set up , run the pattern with marking compound to be sure the pinion depth/backlash is correct. good luck,crazyL __________________ 69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears....

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