71 C20 rear end #'s - The 1947 - Present Chevrolet & GMC Truck Message Board Network

tricities 65 · 12-24-2003, 08:25 PM

What numbers on the rear end of a 1971 C20 would indicate a 3:73 ring and pinion ratio? Or where can I find the numbers to cross reference the actual ones one the rear end tube? Any help would be gereatly appreciated. Thanks,
Rick

lukecp · 12-24-2003, 09:02 PM

If the cover is taken off the rear, the numbers should be stamped on the ring gear (on a 12 bolt anyway, not sure about a Dana 60 or an HO52).

They would be like 41:10, which would mean 4.10 gears.

Or you could jack the truck in the air, and count how many turns the driveshaft makes from one turn on the wheel. If it was about 4 exactly, you would have 4.10 gears, about 4.5 would be 4.56, ect.

Good luck

Solver · 12-24-2003, 11:15 PM

I checked my book and it shows no 3:73 for a c-20 1971
my book lists for 71 C-20:
3:54
4:10
4:56
4:57
It does show a g-20 (whatever that is) as having a 3:73 available
3 letter code for a G-20 3:73 is TPJ
3 letter code for a G-20 3:73 posi TPK

1972 doesn't show a listing for C-20 with 3:73 either
1970 shows a GA-20 (what ever that is ) with 3:73

tricities 65 · 12-24-2003, 11:30 PM

thanks, very helpful!

Duallie · 12-24-2003, 11:33 PM

A G20 is a van. P30 is a 1 ton class A motorhome.

Mike C · 12-25-2003, 11:28 AM

The Dana rear axles all came with a tag that tells what ratio the axle has. The tag is similar to a 12 bolt limited slip fluid tag, a metal thing that bolts to one of the cover bolts. It will have the ring and pinion numbers (41:10 etc.) stamped on the tag along with a part # for the axle assembly from Dana. UNLESS some past owner changed diff fluid and saw no reason to put it back. Highly irritating...

tricities 65 · 12-25-2003, 11:55 AM

i'm going to look at the truck tomorrow with hopes of buying it. The owner did say the tag was missing. Looks like I'm going to just have to jack it up and spin the wheels! Thanks

12-24-2003, 08:25 PM	#1
tricities 65 Registered User Join Date: Nov 2003 Posts: 6	71 C20 rear end #'s What numbers on the rear end of a 1971 C20 would indicate a 3:73 ring and pinion ratio? Or where can I find the numbers to cross reference the actual ones one the rear end tube? Any help would be gereatly appreciated. Thanks, Rick

12-24-2003, 09:02 PM	#2
lukecp Formerly yellow72custom Join Date: May 2001 Location: Austin, TX Posts: 7,531	If the cover is taken off the rear, the numbers should be stamped on the ring gear (on a 12 bolt anyway, not sure about a Dana 60 or an HO52). They would be like 41:10, which would mean 4.10 gears. Or you could jack the truck in the air, and count how many turns the driveshaft makes from one turn on the wheel. If it was about 4 exactly, you would have 4.10 gears, about 4.5 would be 4.56, ect. Good luck __________________ '72 Chevy C10 Mild 350/TH350/3.07. Ochre/White. Old high school ride. '70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck. '97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg

12-24-2003, 11:15 PM	#3
Solver Registered User Join Date: May 2000 Location: Storm Lake, Ia Posts: 1,449	I checked my book and it shows no 3:73 for a c-20 1971 my book lists for 71 C-20: 3:54 4:10 4:56 4:57 It does show a g-20 (whatever that is) as having a 3:73 available 3 letter code for a G-20 3:73 is TPJ 3 letter code for a G-20 3:73 posi TPK 1972 doesn't show a listing for C-20 with 3:73 either 1970 shows a GA-20 (what ever that is ) with 3:73 __________________ 1972 Cheyenne Super 20 LWB-Blue 1972 Cheyenne Super 10 LWB-Black 1972 Cheyenne Super 10 LWB-Red 1972 Cheyenne Super 10 LWB-green 1972 GMC 4x4 LWB-White 1971 Cheyenne 10 LWB-Ochre 1971 Cheyenne 20 Longhorn-Copper 1971 Cheyenne 20 Longhorn-Black 1969 Custom 10 LWB-lt blue 1968 GMC 3/4 ton-green 1968 1/2 ton swb stepside-silver 1967 Chevrolet CST 10 LWB-green 1967 Chevrolet custom 20 LWB-Maroon Last edited by Solver; 12-24-2003 at 11:26 PM.

12-24-2003, 11:33 PM	#5
Duallie Registered User Join Date: Feb 2001 Location: Nikiski, Alaska Posts: 477	A G20 is a van. P30 is a 1 ton class A motorhome. __________________ Just as if I knew what I was doin'

12-25-2003, 11:28 AM	#6
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,715	The Dana rear axles all came with a tag that tells what ratio the axle has. The tag is similar to a 12 bolt limited slip fluid tag, a metal thing that bolts to one of the cover bolts. It will have the ring and pinion numbers (41:10 etc.) stamped on the tag along with a part # for the axle assembly from Dana. UNLESS some past owner changed diff fluid and saw no reason to put it back. Highly irritating... __________________ 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

12-24-2003, 11:30 PM	#4
tricities 65 Registered User Join Date: Nov 2003 Posts: 6	thanks, very helpful!

12-25-2003, 11:55 AM	#7
tricities 65 Registered User Join Date: Nov 2003 Posts: 6	i'm going to look at the truck tomorrow with hopes of buying it. The owner did say the tag was missing. Looks like I'm going to just have to jack it up and spin the wheels! Thanks



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