Rear end question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Martin64 · 10-15-2003, 08:12 PM

How can I tell what gears I have without actually counting the teeth on them? The truck is all original except the motor. It originally came with a 307 but now it has a 350.

JimKshortstep4x4 · 10-15-2003, 08:32 PM

With the truck on flat level ground, index marks made on your drum and backing plate along with index marks on your yoke and housing, it is easy to do. Roll the truck in a straight line for one turn of the yoke and count the turns of the drum. If the drum turns just over three turns, then it is a 3:07, if it turns more then that you can tell if it is a 3:73, (almost 4 turns). It probably will be one or the other but it does not have to be as anything can happen to these trucks!

Jim

Martin64 · 10-16-2003, 12:16 AM

Thanks Jim. The reason I ask is because I think it's turning quite a few rpm at highway speed and, one way or another, I want to get the rpm down at "cruise altitude" and get better gas mileage...... I know I can get better than 8.75 mpg.

Longhorn Man · 10-16-2003, 12:35 AM

If your truck has an automatic, then it should have a 3.07 gear. That is the lowest RPM gear that came stock in it.
If you have a 3 or a 4 speed, then (if I am not mistaken) it'll be a 3.73 gear.
This is asuming nothing is listed in the glove box option sheet and it is indeed stock.
Dropping the oil out and counting the teeth is not a bad idea, the oil is probably original too.

Martin64 · 10-16-2003, 12:41 AM

It has the original Power Glide. I checked the build sheet and it does sasy "Power Glide" on it..... so does that mean it was an option?

Longhorn Man · 10-16-2003, 12:46 AM

yes, anything listed on that is not considered base model equipment.
With a powerglide, that would make it a 67/68, I'll have to double check on my gear quotes up there, but I am pretty sure I am still right...just wanna double check.

Martin64 · 10-16-2003, 01:02 AM

It's a '70. It was originally owned (and ordered) by the Oceanside (Ca.) Fire Department. It also has:

Model CE10704 W/ Base 115
G50- H D Rear Spring
F51- Front and Rear Shock
K76- 61 Amp Delco Gen
E60- H D Battery
1001FC- Special Paint

The VIN is CE140Z2152531 if that has any hidden info

Longhorn Man · 10-16-2003, 01:17 AM

Interesting...I thought the Powerglide option was killed in 69 when the Th350 was introduced.
CE140Z2152531
This decodes to;
C - 2 wheel drive
E - v-8 engine. (307 onless otherwise stated on option sheet)
1 - 1/2 ton
4 - Pickup with Cab and Bed
0 - 1970
Z - Fremont (california...not Ohio)

2152531 - 1152531th unit built in that plant for that given model year. (100001 = 1st Unit Built)
Being a retired fire truck, it probably only has 20,000 miles on it, but I'll pretty much gurantee that the oil in the diff is original. They never do anything they don't have to do when it comes to maintaining there trucks. We maintain the trucks in a small fire department here, and I recently drained the oil out of a 1976 C/50 fire truck that had not had an oil chainge since 1995 according to our records.

10-15-2003, 08:12 PM	#1
Martin64 Registered User Join Date: Oct 2003 Location: Yuma, Az Posts: 477	Rear end question How can I tell what gears I have without actually counting the teeth on them? The truck is all original except the motor. It originally came with a 307 but now it has a 350. __________________ Martin Gibson USAF Retired 1964(-ish) C10

10-16-2003, 12:16 AM	#3
Martin64 Registered User Join Date: Oct 2003 Location: Yuma, Az Posts: 477	Thanks Jim. The reason I ask is because I think it's turning quite a few rpm at highway speed and, one way or another, I want to get the rpm down at "cruise altitude" and get better gas mileage...... I know I can get better than 8.75 mpg. __________________ Martin Gibson USAF Retired 1964(-ish) C10

10-16-2003, 12:41 AM	#5
Martin64 Registered User Join Date: Oct 2003 Location: Yuma, Az Posts: 477	It has the original Power Glide. I checked the build sheet and it does sasy "Power Glide" on it..... so does that mean it was an option? __________________ Martin Gibson USAF Retired 1964(-ish) C10

10-16-2003, 01:02 AM	#7
Martin64 Registered User Join Date: Oct 2003 Location: Yuma, Az Posts: 477	It's a '70. It was originally owned (and ordered) by the Oceanside (Ca.) Fire Department. It also has: Model CE10704 W/ Base 115 G50- H D Rear Spring F51- Front and Rear Shock K76- 61 Amp Delco Gen E60- H D Battery 1001FC- Special Paint The VIN is CE140Z2152531 if that has any hidden info __________________ Martin Gibson USAF Retired 1964(-ish) C10

10-15-2003, 08:32 PM	#2
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	With the truck on flat level ground, index marks made on your drum and backing plate along with index marks on your yoke and housing, it is easy to do. Roll the truck in a straight line for one turn of the yoke and count the turns of the drum. If the drum turns just over three turns, then it is a 3:07, if it turns more then that you can tell if it is a 3:73, (almost 4 turns). It probably will be one or the other but it does not have to be as anything can happen to these trucks! Jim

10-16-2003, 12:35 AM	#4
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	If your truck has an automatic, then it should have a 3.07 gear. That is the lowest RPM gear that came stock in it. If you have a 3 or a 4 speed, then (if I am not mistaken) it'll be a 3.73 gear. This is asuming nothing is listed in the glove box option sheet and it is indeed stock. Dropping the oil out and counting the teeth is not a bad idea, the oil is probably original too.

10-16-2003, 12:46 AM	#6
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	yes, anything listed on that is not considered base model equipment. With a powerglide, that would make it a 67/68, I'll have to double check on my gear quotes up there, but I am pretty sure I am still right...just wanna double check.

10-16-2003, 01:17 AM	#8
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Interesting...I thought the Powerglide option was killed in 69 when the Th350 was introduced. CE140Z2152531 This decodes to; C - 2 wheel drive E - v-8 engine. (307 onless otherwise stated on option sheet) 1 - 1/2 ton 4 - Pickup with Cab and Bed 0 - 1970 Z - Fremont (california...not Ohio) 2152531 - 1152531th unit built in that plant for that given model year. (100001 = 1st Unit Built) Being a retired fire truck, it probably only has 20,000 miles on it, but I'll pretty much gurantee that the oil in the diff is original. They never do anything they don't have to do when it comes to maintaining there trucks. We maintain the trucks in a small fire department here, and I recently drained the oil out of a 1976 C/50 fire truck that had not had an oil chainge since 1995 according to our records.



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