1972-c10....trans swap=shorter driveshaft? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

DuckhunterInTN · 07-21-2003, 10:29 AM

I am looking at a 1972 c10. The fella said that he swapped in a rebuilt 350 motor and a turbo 350 trans. He said the truck came stock with a V-8 and a auto trans. He said that all the truck needs is a new driveshaft because the stock one won't work (either too long or short). Would this be the case??? What v-8/auto trans combo would have been shorter/longer? Or does this sound like an excuse or a hack job?

**CPNE** · 07-21-2003, 10:39 AM

2 things may make a difference:

1. relocating the V8 in the I6 position (sits closer to firewall)
2. Long tailshaft tranny (9 inch) vs stock short tailshaft (6 inch).

Either one of these will make the shaft too long, I can't think of an instance where it would be too short, given the truck was a small block/auto from the factory.

The other thing that may be wrong with the OE driveshaft is the slip yolk. A th400 yolk is different than a th350 yolk in diameter. I think the length of the yolk is the same however.

Tx Firefighter · 07-21-2003, 10:42 AM

Measure the length of the tailhousing on the trans. It bolts onto the back of the trans with 4 bolts. Depending on the length, you might have to get a new shaft made.

TH350s came in three different lengths

Get back to us with the length, it should be 6,9, or 12 inches long

DuckhunterInTN · 07-21-2003, 10:52 AM

So the guy is probably not blowing smoke, huh? He has this truck for $850 and says it is ready to run except it needs the exhaust collectors and a new driveshaft made because the stock one doesn't fit. The guy seems like a nice guy but I am a little cautious because both of those "problems" basically keep me from checking the motor or the trans to see if they are in good working order.

Plus, even if they do work I don't want to buy some truck that has had it's crossmembers all hacked up to make a too long trans fit.

Tx Firefighter · 07-21-2003, 11:35 AM

Don't sweat the trans length issue. No matter which length of TH350 he put in there, there is no reason to hack any crossmembers. The length of the tailhousing is behind the mount pad. That is, any TH350 will have the crossmember mounted in the same place.

No matter what, after you get the driveshaft in, the problem will be solved for good.

DuckhunterInTN · 07-21-2003, 11:56 AM

I guess so will the question of whether or not the thing has a functioning transmission

Longhorn Man · 07-21-2003, 07:07 PM

To fire the engine with out messin up the tranny, you can unbolt the converter and slide it back off the fly wheel.
But you still wouldn't know if the tranny is any good though.

DuckhunterInTN · 07-21-2003, 07:40 PM

Well the trans and motor are all bolted up so I don't think there would be any harm in firing it up b/c it was missing the driveshaft, would it? The issue with not being able to firing it up is the exhaust manifolds not being bolted up...

Longhorn Man · 07-21-2003, 07:57 PM

You can fire it with no manifolds. I wouldn't run it up to operating temps. I'd just fire it to see for knocks, misses, and smoke, then kill it. No damage will be done if it is warm out. (do it in sub zero temps and it may well kill a valve.)
If you leave the verter hooked up and start it, oil may shoot out the tail shaft, (not 100% sure on that one) and since the tranny is probably pretty much empty, it can cause quite a bit of damage.
However, i have run an engine about 1 hr all in all (a little at a time to tune it) There was no oil in the tranny, a fresh rebuild. Only one qt in the verter (which was bolted up to the fly wheel). To this day I have not yet had a problem with it.
But it does do damage now that I know what I know.

DuckhunterInTN · 07-22-2003, 12:34 PM

I figured that the driveshaft just bolted to the back of the trans and that you could run it no problems....kinda like when you remove the front or rear driveshaft from a 4x4 in order to get home with a busted axle....

Longhorn Man · 07-22-2003, 04:04 PM

On an automatic it slides into the tranny.

07-21-2003, 10:29 AM	#1
DuckhunterInTN Registered User Join Date: Feb 2003 Location: Brownsville, TN Posts: 88	1972-c10....trans swap=shorter driveshaft? I am looking at a 1972 c10. The fella said that he swapped in a rebuilt 350 motor and a turbo 350 trans. He said the truck came stock with a V-8 and a auto trans. He said that all the truck needs is a new driveshaft because the stock one won't work (either too long or short). Would this be the case??? What v-8/auto trans combo would have been shorter/longer? Or does this sound like an excuse or a hack job? __________________ 2004 GMC 2500HD 4x4 Crew Cab Duramax 2000 Chevrolet ext-cab Z71 1995 Chevrolet ext-cab Z71 1984 Chevrolet K10 6.2 4x4 1972 GMC Jimmy 4x4 1967 Chevrolet C50 Dump truck 1957 GMC 1/2 ton stepside (not running)

07-21-2003, 10:39 AM	#2
CPNE Resident Curmudgeon Join Date: Dec 1999 Location: NH Posts: 6,664	2 things may make a difference: 1. relocating the V8 in the I6 position (sits closer to firewall) 2. Long tailshaft tranny (9 inch) vs stock short tailshaft (6 inch). Either one of these will make the shaft too long, I can't think of an instance where it would be too short, given the truck was a small block/auto from the factory. The other thing that may be wrong with the OE driveshaft is the slip yolk. A th400 yolk is different than a th350 yolk in diameter. I think the length of the yolk is the same however. __________________ Currently on or near the homestead: 67 Chevy SWB 2WD stepside 350/3 on tree (Pat's) 67 GMC SWB 2WD Fleet 402/auto (Brian's under construction) 67 Chevy 3/4 ton 2WD 402/auto (Business Hauler) 67 Chevy 1 ton dually 2WD 396/4 speed (Former business hauler, Needs TLC) 68 Chevy 1/2 ton Suburban 2WD 250 six/3 on tree (Brian's Needs TLC) 70 Chevy 3/4 ton 4WD 350/4 speed (Pat's - Disguised as a 68 GMC) 71 Chevy SWB stepside (Crushed by tree - parts donor) 72 Chevy 3/4 ton 4WD (Parts donor) 72 Chevy 3/4 ton 4WD Suburban (Parts Donor) 72 GMC 3/4 ton 4WD 292 six/4 speed (Mine - Disguised as a 67 GMC) 81 GMC 4WD Dually Dump Body 350/4 speed (Business Hauler) 82 Camaro Z/28 355/Super T-10 (Pat's toy) 93 Caprice 9C1 (Brian's Cop Car) 02 Toyota Camry (Reliable but a souless steel and plastic hulk) 2011 2SS RS Camaro M6 Factory Hurst Shifter Maybe I need to sell some of this crap Yet another Bozo with a sawz-all

07-21-2003, 10:52 AM	#4
DuckhunterInTN Registered User Join Date: Feb 2003 Location: Brownsville, TN Posts: 88	So the guy is probably not blowing smoke, huh? He has this truck for $850 and says it is ready to run except it needs the exhaust collectors and a new driveshaft made because the stock one doesn't fit. The guy seems like a nice guy but I am a little cautious because both of those "problems" basically keep me from checking the motor or the trans to see if they are in good working order. Plus, even if they do work I don't want to buy some truck that has had it's crossmembers all hacked up to make a too long trans fit. __________________ 2004 GMC 2500HD 4x4 Crew Cab Duramax 2000 Chevrolet ext-cab Z71 1995 Chevrolet ext-cab Z71 1984 Chevrolet K10 6.2 4x4 1972 GMC Jimmy 4x4 1967 Chevrolet C50 Dump truck 1957 GMC 1/2 ton stepside (not running)

07-21-2003, 11:56 AM	#6
DuckhunterInTN Registered User Join Date: Feb 2003 Location: Brownsville, TN Posts: 88	I guess so will the question of whether or not the thing has a functioning transmission __________________ 2004 GMC 2500HD 4x4 Crew Cab Duramax 2000 Chevrolet ext-cab Z71 1995 Chevrolet ext-cab Z71 1984 Chevrolet K10 6.2 4x4 1972 GMC Jimmy 4x4 1967 Chevrolet C50 Dump truck 1957 GMC 1/2 ton stepside (not running)

07-21-2003, 07:40 PM	#8
DuckhunterInTN Registered User Join Date: Feb 2003 Location: Brownsville, TN Posts: 88	Well the trans and motor are all bolted up so I don't think there would be any harm in firing it up b/c it was missing the driveshaft, would it? The issue with not being able to firing it up is the exhaust manifolds not being bolted up... __________________ 2004 GMC 2500HD 4x4 Crew Cab Duramax 2000 Chevrolet ext-cab Z71 1995 Chevrolet ext-cab Z71 1984 Chevrolet K10 6.2 4x4 1972 GMC Jimmy 4x4 1967 Chevrolet C50 Dump truck 1957 GMC 1/2 ton stepside (not running)

07-21-2003, 10:42 AM	#3
Tx Firefighter Watch out for your cornhole ! Join Date: Jun 2003 Location: Azle, Texas Posts: 14,162	Measure the length of the tailhousing on the trans. It bolts onto the back of the trans with 4 bolts. Depending on the length, you might have to get a new shaft made. TH350s came in three different lengths Get back to us with the length, it should be 6,9, or 12 inches long

07-21-2003, 11:35 AM	#5
Tx Firefighter Watch out for your cornhole ! Join Date: Jun 2003 Location: Azle, Texas Posts: 14,162	Don't sweat the trans length issue. No matter which length of TH350 he put in there, there is no reason to hack any crossmembers. The length of the tailhousing is behind the mount pad. That is, any TH350 will have the crossmember mounted in the same place. No matter what, after you get the driveshaft in, the problem will be solved for good.

07-21-2003, 07:07 PM	#7
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	To fire the engine with out messin up the tranny, you can unbolt the converter and slide it back off the fly wheel. But you still wouldn't know if the tranny is any good though.

07-21-2003, 07:57 PM	#9
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	You can fire it with no manifolds. I wouldn't run it up to operating temps. I'd just fire it to see for knocks, misses, and smoke, then kill it. No damage will be done if it is warm out. (do it in sub zero temps and it may well kill a valve.) If you leave the verter hooked up and start it, oil may shoot out the tail shaft, (not 100% sure on that one) and since the tranny is probably pretty much empty, it can cause quite a bit of damage. However, i have run an engine about 1 hr all in all (a little at a time to tune it) There was no oil in the tranny, a fresh rebuild. Only one qt in the verter (which was bolted up to the fly wheel). To this day I have not yet had a problem with it. But it does do damage now that I know what I know.

07-22-2003, 12:34 PM	#10
DuckhunterInTN Registered User Join Date: Feb 2003 Location: Brownsville, TN Posts: 88	I figured that the driveshaft just bolted to the back of the trans and that you could run it no problems....kinda like when you remove the front or rear driveshaft from a 4x4 in order to get home with a busted axle.... __________________ 2004 GMC 2500HD 4x4 Crew Cab Duramax 2000 Chevrolet ext-cab Z71 1995 Chevrolet ext-cab Z71 1984 Chevrolet K10 6.2 4x4 1972 GMC Jimmy 4x4 1967 Chevrolet C50 Dump truck 1957 GMC 1/2 ton stepside (not running)

07-22-2003, 04:04 PM	#11
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	On an automatic it slides into the tranny.



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