New Member with 1981 C10 Question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

MirandaB · 05-04-2012, 08:15 PM

Hi Everyone.

My name is Miranda. I have a 1981 C10 2WD SB, 4.1L straight six, and 4-speed manual transmission with OD, and I need some advice.

I bought the truck a few months ago from the original owner. It has about 65K miles on it. The cab is in decent shape, but needs new rocker panels and inner fenders. The bed is shot.

The truck tends to bog down easily, and to help counteract that I have rebuilt the 2BBL carb and installed a new fuel pump. The engine runs fine, but the differential gear ratio is still too high. I checked it yesterday by counting wheel revolutions x2 and counting the driveshaft revs, and it is approximately 2.75. I checked the RPO codes on the truck and there isn't any special code for the differential gearing on mine.

The rear end is a 10-bolt, 8.5 inch as far as I can tell.

Does anyone know what the other standard gearings are for the 1981 C10 with a 4.1L engine?

I am going to look at a used rear end for a 1997 Chevy 1/2T tomorrow. Other than checking perch centers and the u-joint dimension, can anyone suggest anything else I should look for?

Thanks,

Miranda

OneClean86 · 05-05-2012, 10:58 AM

I do know that the more common of the gear ratios are 2:73, 3:73, and 4:10. So I would think that your running 2:73 then? Correct me if I'm wrong.

hotrod_991 · 05-05-2012, 11:23 AM

sounds about right. I would deff get yourself some 3:73's it will help out alot.

Dalaigh · 05-05-2012, 11:23 AM

If there isn't an RPO code for the gears it's probably 2.73's. The rear is an 8.5" 10 bolt.

With the 97 rear end the spring perches are going to be different then the 73-87's. If you're not worried about that and plan to weld on new perches, the only other thing I would check is if theres any slop in the pinion and check the condition of the gears of the axle.

Sounds like you've got a nice little rolling project, good luck.

MirandaB · 05-06-2012, 11:51 AM

Hi Guys,

Thanks so much for your input.

The perches on the 97 rear end were on wider centers, so it wouldn't have been a direct replacement. There is a well-stocked salvage yard about 20 miles from here that may have a direct replacement in 3.73 or something close. I'll give them a try.

I'll also try to post some project pics soon - at the moment they will mostly fall into the "Before" category, though.

Thanks again for your help,

Miranda

05-04-2012, 08:15 PM	#1
MirandaB Registered User Join Date: May 2012 Location: Naples, NY Posts: 5	New Member with 1981 C10 Question Hi Everyone. My name is Miranda. I have a 1981 C10 2WD SB, 4.1L straight six, and 4-speed manual transmission with OD, and I need some advice. I bought the truck a few months ago from the original owner. It has about 65K miles on it. The cab is in decent shape, but needs new rocker panels and inner fenders. The bed is shot. The truck tends to bog down easily, and to help counteract that I have rebuilt the 2BBL carb and installed a new fuel pump. The engine runs fine, but the differential gear ratio is still too high. I checked it yesterday by counting wheel revolutions x2 and counting the driveshaft revs, and it is approximately 2.75. I checked the RPO codes on the truck and there isn't any special code for the differential gearing on mine. The rear end is a 10-bolt, 8.5 inch as far as I can tell. Does anyone know what the other standard gearings are for the 1981 C10 with a 4.1L engine? I am going to look at a used rear end for a 1997 Chevy 1/2T tomorrow. Other than checking perch centers and the u-joint dimension, can anyone suggest anything else I should look for? Thanks, Miranda

05-05-2012, 10:58 AM	#2
OneClean86 Registered User Join Date: Apr 2012 Location: Jefferson City Posts: 2	Re: New Member with 1981 C10 Question I do know that the more common of the gear ratios are 2:73, 3:73, and 4:10. So I would think that your running 2:73 then? Correct me if I'm wrong.

05-05-2012, 11:23 AM	#3
hotrod_991 Registered User Join Date: Jul 2009 Location: Thibodaux, LA Posts: 479	Re: New Member with 1981 C10 Question sounds about right. I would deff get yourself some 3:73's it will help out alot. __________________ "Buckle up I wanna try somethin!!" "of course it will hold!, I welded it!" 1977 c10 under knife for full rebuild, 5.3l 4l60e drive rain swap, replacement frame and green repaint

05-05-2012, 11:23 AM	#4
Dalaigh Canadian Trucker Join Date: Nov 2010 Location: Sarnia, ont canada Posts: 648	Re: New Member with 1981 C10 Question If there isn't an RPO code for the gears it's probably 2.73's. The rear is an 8.5" 10 bolt. With the 97 rear end the spring perches are going to be different then the 73-87's. If you're not worried about that and plan to weld on new perches, the only other thing I would check is if theres any slop in the pinion and check the condition of the gears of the axle. Sounds like you've got a nice little rolling project, good luck. __________________ 2020 Silverado Trail Boss - 6.2/10spd

05-06-2012, 11:51 AM	#5
MirandaB Registered User Join Date: May 2012 Location: Naples, NY Posts: 5	Re: New Member with 1981 C10 Question Hi Guys, Thanks so much for your input. The perches on the 97 rear end were on wider centers, so it wouldn't have been a direct replacement. There is a well-stocked salvage yard about 20 miles from here that may have a direct replacement in 3.73 or something close. I'll give them a try. I'll also try to post some project pics soon - at the moment they will mostly fall into the "Before" category, though. Thanks again for your help, Miranda



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