3:73 gear to 3:42 gear ????? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

bigblock79 · 07-21-2007, 10:07 PM

can i take a 3:73 posi and put a set of 3:42 gears in it or vice a versus. thanks

Ivan D. · 07-21-2007, 11:48 PM

as long as both came off the same type axles (i.e. both are 12-bolts, or both are 10-bolts) the crowns and pinions should swap out just fine

piecesparts · 07-21-2007, 11:49 PM

Sure you can, but you have to carefull as to whcih carrier you have. There are two different sizes and the difference is how thick the ring gear has to be. I went from a 3.42 gearing to a 3.73 gearing, but I had a smaller carrier size and I had to make sure of the right gear parts. Check in with Randy's ring and Pinion for advice. Just call him, he will tell you what you need to know.

benoit454 · 07-22-2007, 12:09 AM

I thought as far as carrier seris went it had to be numerically pretty low to have a 2 series, like 2.xx gear ratio, and 3.xx for 3 series.

I'm not sure though, that's basically how it was for the 80's g bodys, I think it's 3.08 and numerically lower was 2 series, and then 3.42 or anything above 3.08 was 3 series.

krue · 07-22-2007, 01:10 AM

Is it 3.42 or 3.40? I pulled a rearend out of a 74 and it had 10:34 on the ring gear, which works out to 3.40 even, right?

piecesparts · 07-22-2007, 09:36 AM

First of all, the breaking point for the carriers is around the 3.42 mark. There were the larger carriers with a 3.42 gear and then there were the smaller carriers with a 3.42 gear on them. The aftermarket makes a 3.73 gear to go into the smaller carrier design and they also have a 3.73 for the larger design. My 12 bolt posi setups in the 84 and the 86 trucks are Eaton units and the carriers are both the smaller design.

My calculations on the ring and pinion makes mine come out to be 3.41556.... or 3.42.

bigblock79 · 07-22-2007, 09:51 AM

the 3;42 is in a 87 chevy truck it says 3;42 on the glove box and the 3:73 came out of a 73-75 and iwas just wondering ig i can put the 342 gears on the 373 rearend they are both 12 bolt thanks

**special-K** · 07-22-2007, 10:42 AM

I think that 3.73 is in either series and you`d be safe going to 3.42s with the same series.

piecesparts · 07-22-2007, 10:45 AM

I still support that it depends on which carrier unit you have. Maybe you could just swap the whole rearend.

Donnylee · 07-22-2007, 12:13 PM

Question. What would possible donor vehicles be for a complete 3:73 rear swap that will just bolt into an 1984 Stepside? Are the rears on steppers narrower then regular square beds?

Thank in advance for the help!

Donny

bigblock79 · 07-22-2007, 01:38 PM

the 373 is a posi and i would rather not have that low of a gear i rather have the 342 on the posi

07-21-2007, 10:07 PM	#1
bigblock79 67 Chevy Stepside Join Date: Mar 2007 Location: Jonesville NC Posts: 836	3:73 gear to 3:42 gear ????? can i take a 3:73 posi and put a set of 3:42 gears in it or vice a versus. thanks __________________ 1967 Chevy stepside 1976 BIG DOOLEY 454 turbo 400 4:11

07-21-2007, 11:48 PM	#2
Ivan D. glamoros piece o' lowlife Join Date: Mar 2007 Location: Redford, MI Posts: 1,164	Re: 3:73 gear to 3:42 gear ????? as long as both came off the same type axles (i.e. both are 12-bolts, or both are 10-bolts) the crowns and pinions should swap out just fine __________________ The more I drink, the more I drink, the more I drink... diesel, reg cab, long bed, 4 across the rear, single stack, wooden stakes, and lotsa lights - the Hay Express

07-21-2007, 11:49 PM	#3
piecesparts Parts and more parts Join Date: Nov 2003 Location: Lebo, Kansas (middle of nowhere Posts: 6,821	Re: 3:73 gear to 3:42 gear ????? Sure you can, but you have to carefull as to whcih carrier you have. There are two different sizes and the difference is how thick the ring gear has to be. I went from a 3.42 gearing to a 3.73 gearing, but I had a smaller carrier size and I had to make sure of the right gear parts. Check in with Randy's ring and Pinion for advice. Just call him, he will tell you what you need to know.

07-22-2007, 12:09 AM	#4
benoit454 Chris Join Date: Nov 2004 Location: Monaville, WV Posts: 3,737	Re: 3:73 gear to 3:42 gear ????? I thought as far as carrier seris went it had to be numerically pretty low to have a 2 series, like 2.xx gear ratio, and 3.xx for 3 series. I'm not sure though, that's basically how it was for the 80's g bodys, I think it's 3.08 and numerically lower was 2 series, and then 3.42 or anything above 3.08 was 3 series. __________________ Chris GIT R DONE!!!!!! Check out all our rides, http://www.cardomain.com/id/benwa454

07-22-2007, 01:10 AM	#5
krue Designated A-hole! Join Date: Mar 2003 Location: South Mississippi Posts: 36,448	Re: 3:73 gear to 3:42 gear ????? Is it 3.42 or 3.40? I pulled a rearend out of a 74 and it had 10:34 on the ring gear, which works out to 3.40 even, right? __________________ "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"

07-22-2007, 09:36 AM	#6
piecesparts Parts and more parts Join Date: Nov 2003 Location: Lebo, Kansas (middle of nowhere Posts: 6,821	Re: 3:73 gear to 3:42 gear ????? First of all, the breaking point for the carriers is around the 3.42 mark. There were the larger carriers with a 3.42 gear and then there were the smaller carriers with a 3.42 gear on them. The aftermarket makes a 3.73 gear to go into the smaller carrier design and they also have a 3.73 for the larger design. My 12 bolt posi setups in the 84 and the 86 trucks are Eaton units and the carriers are both the smaller design. My calculations on the ring and pinion makes mine come out to be 3.41556.... or 3.42.

07-22-2007, 09:51 AM	#7
bigblock79 67 Chevy Stepside Join Date: Mar 2007 Location: Jonesville NC Posts: 836	Re: 3:73 gear to 3:42 gear ????? the 3;42 is in a 87 chevy truck it says 3;42 on the glove box and the 3:73 came out of a 73-75 and iwas just wondering ig i can put the 342 gears on the 373 rearend they are both 12 bolt thanks __________________ 1967 Chevy stepside 1976 BIG DOOLEY 454 turbo 400 4:11

07-22-2007, 10:42 AM	#8
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,851	Re: 3:73 gear to 3:42 gear ????? I think that 3.73 is in either series and you`d be safe going to 3.42s with the same series. __________________ "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 ~

07-22-2007, 10:45 AM	#9
piecesparts Parts and more parts Join Date: Nov 2003 Location: Lebo, Kansas (middle of nowhere Posts: 6,821	Re: 3:73 gear to 3:42 gear ????? I still support that it depends on which carrier unit you have. Maybe you could just swap the whole rearend.

07-22-2007, 12:13 PM	#10
Donnylee Registered User Join Date: Feb 2007 Location: Oregon Posts: 44	Re: 3:73 gear to 3:42 gear ????? Question. What would possible donor vehicles be for a complete 3:73 rear swap that will just bolt into an 1984 Stepside? Are the rears on steppers narrower then regular square beds? Thank in advance for the help! Donny __________________ Would you rather be eating Government Cheese down by the river, and living in a C-10~!

07-22-2007, 01:38 PM	#11
bigblock79 67 Chevy Stepside Join Date: Mar 2007 Location: Jonesville NC Posts: 836	Re: 3:73 gear to 3:42 gear ????? the 373 is a posi and i would rather not have that low of a gear i rather have the 342 on the posi __________________ 1967 Chevy stepside 1976 BIG DOOLEY 454 turbo 400 4:11



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