reading vin for gears? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

timamin · 06-21-2006, 10:19 PM

can I find out what gears I have in the rear end of my truck by the vin? there are some num/letters on the axle but I dunno if that would help find what gears I have. also anyone know a site that lists what gears came in '72 c20 trucks with a 4 speed manual and 292.

**'68OrangeSunshine** · 06-21-2006, 10:32 PM

Unless I missed something, I don't think you can tell your rear end gearing by the VIN. Best way is to pull off the differential cover and count the teeth. --m (Of course you have to change the differential oil anyway)
A less messy, but less accurate way is to count how many times the wheel spins against how many turns you get out of the differential yoke with the entire rear propped up on jackstands.
Rear end gear ratios are often listed on the glove box door sticker, as an RPO number [Retail Purchase Option] but that's usually if it's a special order. . .
Offhand, 3.73:1 is common for 1/2 tons and 4.11:1 is more usual for 3/4 tons.

Longhorn Man · 06-21-2006, 11:13 PM

RPO is Regular Production Option... for NON special order parts, but rather for options offered on that model of vehicle.
Assuming your truck has not been modified, and it came with a 292 and the 4 speed, and no options were listed for gears, then you have the 4.10 gear.

yourgrool · 06-22-2006, 01:45 AM

there should be 2 numbers on the ring gear for example 41 11 and you divide those and get 3.7272 something and that means 3.73 gears. Thats what i have found on a stock 12 bolt out of a 72 gmc 1/2 ton.

KFreddy · 06-22-2006, 05:57 AM

Trying to figure out the same thing months ago. I jacked up the back of the truck, placed a mark on both the drive shaft and the tire. Turn the tire a full 360 while counting how many times that mark on the drive shaft moves past a fixed point. I got 3.07 and change = 3.08 rear end. Not that it matters with a ZZ454

**'68OrangeSunshine** · 06-23-2006, 12:00 AM

Quote:

Originally Posted by Longhorn Man

RPO is Regular Production Option... for NON special order parts, but rather for options offered on that model of vehicle.
Assuming your truck has not been modified, and it came with a 292 and the 4 speed, and no options were listed for gears, then you have the 4.10 gear.

OK Andy, I knew it stood for something like that. But was it 4.10 or 4.11?

Solver · 06-23-2006, 12:38 AM

If you can get me the numbers off the axle tube in the area circled in red I can tell you what they id. Long as they are the original gears still in the rear end.
Usually 3 letters then numbers only need the letters

Longhorn Man · 06-23-2006, 07:22 PM

on a 20 or 30 series it is a 4.10 ... on a 10 series, 4.11.

**'68OrangeSunshine** · 06-24-2006, 09:22 PM

Quote:

Originally Posted by Longhorn Man

on a 20 or 30 series it is a 4.10 ... on a 10 series, 4.11.

Well, ya learn something new every day.

robsm88 · 06-25-2006, 12:59 AM

Quote:

Originally Posted by Solver

If you can get me the numbers off the axle tube in the area circled in red I can tell you what they id. Long as they are the original gears still in the rear end.
Usually 3 letters then numbers only need the letters

Sorry to jump on this thread, but it is exactly what I was looking for.
Any way you could help me figure this one out. In that circled red area i have;

RHS W259 2

Solver · 06-25-2006, 08:48 AM

RHS is listed as 1972 C10 with 3:07 --- no posi

chevroletman19712001 · 06-25-2006, 11:54 AM

i know this is in the wrong section but if i got the numbers could you guys id a 79 12 bolt?

06-21-2006, 10:19 PM	#1
timamin Registered User Join Date: Jun 2002 Location: san antonio Posts: 52	reading vin for gears? can I find out what gears I have in the rear end of my truck by the vin? there are some num/letters on the axle but I dunno if that would help find what gears I have. also anyone know a site that lists what gears came in '72 c20 trucks with a 4 speed manual and 292. __________________ '72 custom 20 Current mods race built chevy 400 engine. over carbed =/ Powder coated bumpers Progressive Wheels Future mods single windows. alum. fuel cell under bed, sidemarker fuel cap mod. All white and yellow interior. leather bucket seats.

06-21-2006, 10:32 PM	#2
'68OrangeSunshine Senior Member Join Date: Feb 2002 Location: Tucson, AZ USA Posts: 7,517	Re: reading vin for gears? Unless I missed something, I don't think you can tell your rear end gearing by the VIN. Best way is to pull off the differential cover and count the teeth. --m (Of course you have to change the differential oil anyway) A less messy, but less accurate way is to count how many times the wheel spins against how many turns you get out of the differential yoke with the entire rear propped up on jackstands. Rear end gear ratios are often listed on the glove box door sticker, as an RPO number [Retail Purchase Option] but that's usually if it's a special order. . . Offhand, 3.73:1 is common for 1/2 tons and 4.11:1 is more usual for 3/4 tons. __________________ Every 25 years I like to rebuild that 292, whether it needs it or not.

06-21-2006, 11:13 PM	#3
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Re: reading vin for gears? RPO is Regular Production Option... for NON special order parts, but rather for options offered on that model of vehicle. Assuming your truck has not been modified, and it came with a 292 and the 4 speed, and no options were listed for gears, then you have the 4.10 gear.

06-22-2006, 01:45 AM	#4
yourgrool 67-72 Join Date: Nov 2005 Location: Milwaukee Wisconsin Posts: 83	Re: reading vin for gears? there should be 2 numbers on the ring gear for example 41 11 and you divide those and get 3.7272 something and that means 3.73 gears. Thats what i have found on a stock 12 bolt out of a 72 gmc 1/2 ton.

06-22-2006, 05:57 AM	#5
KFreddy Active Member Join Date: Apr 2005 Location: Miami, Florida Posts: 286	Re: reading vin for gears? Trying to figure out the same thing months ago. I jacked up the back of the truck, placed a mark on both the drive shaft and the tire. Turn the tire a full 360 while counting how many times that mark on the drive shaft moves past a fixed point. I got 3.07 and change = 3.08 rear end. Not that it matters with a ZZ454 Last edited by KFreddy; 06-22-2006 at 05:58 AM.

06-23-2006, 12:38 AM	#7
Solver Registered User Join Date: May 2000 Location: Storm Lake, Ia Posts: 1,449	Re: reading vin for gears? If you can get me the numbers off the axle tube in the area circled in red I can tell you what they id. Long as they are the original gears still in the rear end. Usually 3 letters then numbers only need the letters Attached Images __________________ 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

06-23-2006, 07:22 PM	#8
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Re: reading vin for gears? on a 20 or 30 series it is a 4.10 ... on a 10 series, 4.11.

06-25-2006, 08:48 AM	#11
Solver Registered User Join Date: May 2000 Location: Storm Lake, Ia Posts: 1,449	Re: reading vin for gears? RHS is listed as 1972 C10 with 3:07 --- no posi __________________ 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

06-25-2006, 11:54 AM	#12
chevroletman19712001 Registered User Join Date: Jun 2006 Location: SC Posts: 47	Re: reading vin for gears? i know this is in the wrong section but if i got the numbers could you guys id a 79 12 bolt? __________________ 71 chevy longhorn 1 ton 79 chevy straight 6 79 burb 454 91 silverado 350 TBI and a few others that my brand loyalty wont permit me to post. Eureka Boys!!!!

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