1979 C10 Transmission info! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Lowerd1 · 07-29-2003, 12:21 PM

I have a 1979 C10 250 inline std cab long bed Auto. I was wandering if there is a way to find out if it has a THM350 or THM400 trans without crawling under it, since they were both available with that engine in 1979 if I am not mistaken?

Here is why I can't crawl under it. The truck was my grandfathers and has sat at my mothers house for like 5 years. Well in that time my step father decided to pile stuff in the bed and around it. The truck has never been driven in those 5 years. My mother gave me the truck becuase she was tired of looking at it and wanted me to restore it, plus its her fathers truck. They live in the country and its summer here so snakes are a problem considering I already found one when I popped the hood and I am not crawling under the truck to look since my step father already said there have been alot more seen around the truck. I will be moving it and all this winter when the snakes are gone. Right now I am stocking up parts to get to work on it. Well I need to know the trans. Is there anyway by like the Vin number I can find out the trans that is in it?

Oh yea you can call me a wuss if you want for not crawling under the truck but I have had way to many close calls with snakes and I have a fear of my luck running short soon. Plus these are poisonous snakes so it would only take one little fang to catch some skin..

Thanks for any help!

bigblock73 · 07-29-2003, 12:33 PM

The VIN won't do you any good. Considering it is 250 powered, I would almost guarantee it is a th350 trans.

You could also corral board member Desert Rat to help you with the snake problem (he collects them as pets)!

...Jeff

Lowerd1 · 07-29-2003, 12:43 PM

Is there any other way then? How about in the interior. Isn't there a parts code list somewhere. I know my GP has a code list in the trunk and I remember my old 72 had a code list in the glove box. Would the code list tell me which trans was is in it?

Also thanks for the help!

**swervin ervin** · 07-29-2003, 01:01 PM

Look on the rpo code list in the glove box. Look for M38 or M40. M38 is a TH350, M40 is a TH400.

Lowerd1 · 07-29-2003, 02:06 PM

Thanks. Thats what I was hopeing for.

**Captkaos** · 07-29-2003, 02:11 PM

It is a TH350. Inlines in 1/2T's didn't get the TH400.

**swervin ervin** · 07-29-2003, 03:07 PM

Like my 87 van. Why in the world would GM stick a 305 in front of a TH400? Just don't make any sense to me.

**Captkaos** · 07-29-2003, 05:09 PM

Quote:

Originally posted by swervin ervin
Like my 87 van. Why in the world would GM stick a 305 in front of a TH400? Just don't make any sense to me.

I would think the van got the TH400 because it was a utility vehicle. Aren't all vans extended vans G20's? I could be wrong on vans though. Plus, GM is crazy.

ElGracho · 07-29-2003, 05:51 PM

Quote:

Originally posted by swervin ervin
Look on the rpo code list in the glove box. Look for M38 or M40. M38 is a TH350, M40 is a TH400.

Those codes don't always work that way. My 75 has the M40 RPO but has TH350 and it's original. I don't know why, but that's how it is on those, I've seen it more than once too...

dacanuck · 07-29-2003, 08:39 PM

Try calling a dealership and asking them to look it up by your serial number. They should be able to tell you anything by that; I had a dealer tell me over the phone my rear gear ratio. Nice and easy.

gldevall · 07-29-2003, 09:51 PM

Quote:

Originally posted by swervin ervin
Like my 87 van. Why in the world would GM stick a 305 in front of a TH400? Just don't make any sense to me.

Why would they stick a 400 behind a V-6?

**Captkaos** · 07-30-2003, 01:02 PM

The 305 V6 was exclusive to GMC, and was only offered from basically 1960-1974. BUT, the 305 was LARGE.

Nvbowtie · 08-03-2003, 07:23 AM

Well to solve the problem of crawling under and finding a new unwanted friend, hook a chain to it and drag it to another location, then look underneth.

Lowerd1 · 08-03-2003, 12:48 PM

I know I could hook a chain to it and pull it. I am going to do that this winter. I am only getting the info on what needs to be replaced and buying the parts now. That way when I get ready to fix it I don't have to keep running back and forth to find parts at a parts store.

doc70sub · 08-03-2003, 02:55 PM

Chech to see if there is a kick-down cable attached to the carb, TH-400's have electric/switched kick-downs that do not use cable actuation. Good luck w/ the new truck....
Thanks!
doc

gchemist · 08-03-2003, 09:25 PM

Quote:

Originally posted by swervin ervin
Why in the world would GM stick a 305 in front of a TH400?

Probably because they are undestructable. :p Mine is on it's third 700R4. This one should out last it unless I do something dumb. 305s like RPMs so a 400th will do nicely between 2000-3000 RPMs.m

07-29-2003, 12:21 PM	#1
Lowerd1 Full Time Loser! Join Date: Feb 2003 Location: Murfreesboro Tennessee Posts: 65	1979 C10 Transmission info! I have a 1979 C10 250 inline std cab long bed Auto. I was wandering if there is a way to find out if it has a THM350 or THM400 trans without crawling under it, since they were both available with that engine in 1979 if I am not mistaken? Here is why I can't crawl under it. The truck was my grandfathers and has sat at my mothers house for like 5 years. Well in that time my step father decided to pile stuff in the bed and around it. The truck has never been driven in those 5 years. My mother gave me the truck becuase she was tired of looking at it and wanted me to restore it, plus its her fathers truck. They live in the country and its summer here so snakes are a problem considering I already found one when I popped the hood and I am not crawling under the truck to look since my step father already said there have been alot more seen around the truck. I will be moving it and all this winter when the snakes are gone. Right now I am stocking up parts to get to work on it. Well I need to know the trans. Is there anyway by like the Vin number I can find out the trans that is in it? Oh yea you can call me a wuss if you want for not crawling under the truck but I have had way to many close calls with snakes and I have a fear of my luck running short soon. Plus these are poisonous snakes so it would only take one little fang to catch some skin.. Thanks for any help! __________________ 1979 C10 - Its being rebuilt. 1978 Silverado - Its being driven. 1995 Grand Prix GTP - Its stock

07-29-2003, 01:01 PM	#4
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	Look on the rpo code list in the glove box. Look for M38 or M40. M38 is a TH350, M40 is a TH400. __________________ Mike 1985 Chevy C-10

07-29-2003, 02:11 PM	#6
Captkaos www.73-87chevytrucks.com Join Date: Dec 1999 Location: Birmingham, AL Posts: 6,935	It is a TH350. Inlines in 1/2T's didn't get the TH400. __________________ Chris Lucas 1973 Chevy C-10 1978 GMC Jimmy (2WD) - SOLD 1987 R10 twin turbo LS 1991 R3500 SRW CrewCab 1985 K5 diesel swapped project 1989 K5 2WD conversion w/ Vette susp Project Captkaos Customs 73-87chevytrucks.com

07-29-2003, 03:07 PM	#7
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	Like my 87 van. Why in the world would GM stick a 305 in front of a TH400? Just don't make any sense to me. __________________ Mike 1985 Chevy C-10

07-29-2003, 08:39 PM	#10
dacanuck Registered User Join Date: Nov 2002 Location: Toronto, Ontario Posts: 85	Try calling a dealership and asking them to look it up by your serial number. They should be able to tell you anything by that; I had a dealer tell me over the phone my rear gear ratio. Nice and easy. __________________ 86 GMC C15 swb. 350/TH350, fully loaded, but wish I had overdrive!

07-29-2003, 12:33 PM	#2
bigblock73 yeller Join Date: Oct 2001 Location: Twin Cities Posts: 13,824	The VIN won't do you any good. Considering it is 250 powered, I would almost guarantee it is a th350 trans. You could also corral board member Desert Rat to help you with the snake problem (he collects them as pets)! ...Jeff

07-29-2003, 12:43 PM	#3
Lowerd1 Full Time Loser! Join Date: Feb 2003 Location: Murfreesboro Tennessee Posts: 65	Is there any other way then? How about in the interior. Isn't there a parts code list somewhere. I know my GP has a code list in the trunk and I remember my old 72 had a code list in the glove box. Would the code list tell me which trans was is in it? Also thanks for the help!

07-29-2003, 02:06 PM	#5
Lowerd1 Full Time Loser! Join Date: Feb 2003 Location: Murfreesboro Tennessee Posts: 65	Thanks. Thats what I was hopeing for.

07-30-2003, 01:02 PM	#12
Captkaos www.73-87chevytrucks.com Join Date: Dec 1999 Location: Birmingham, AL Posts: 6,935	The 305 V6 was exclusive to GMC, and was only offered from basically 1960-1974. BUT, the 305 was LARGE. __________________ Chris Lucas 1973 Chevy C-10 1978 GMC Jimmy (2WD) - SOLD 1987 R10 twin turbo LS 1991 R3500 SRW CrewCab 1985 K5 diesel swapped project 1989 K5 2WD conversion w/ Vette susp Project Captkaos Customs 73-87chevytrucks.com

08-03-2003, 07:23 AM	#13
Nvbowtie Registered User Join Date: Jul 2001 Location: Laughlin, Nv. USA Posts: 700	Well to solve the problem of crawling under and finding a new unwanted friend, hook a chain to it and drag it to another location, then look underneth. __________________ www.unlimited2u.com/chevy Bill 1980 Chevy C-10 Silverado 1988 Chevy Blazer Tahoe

08-03-2003, 12:48 PM	#14
Lowerd1 Full Time Loser! Join Date: Feb 2003 Location: Murfreesboro Tennessee Posts: 65	I know I could hook a chain to it and pull it. I am going to do that this winter. I am only getting the info on what needs to be replaced and buying the parts now. That way when I get ready to fix it I don't have to keep running back and forth to find parts at a parts store. __________________ 1979 C10 - Its being rebuilt. 1978 Silverado - Its being driven. 1995 Grand Prix GTP - Its stock

08-03-2003, 02:55 PM	#15
doc70sub Registered User Join Date: Dec 2000 Location: Thomasville, NC Posts: 669	Chech to see if there is a kick-down cable attached to the carb, TH-400's have electric/switched kick-downs that do not use cable actuation. Good luck w/ the new truck.... Thanks! doc __________________ 1970 Sub C-10 - 350/TH-350/3.73 12-bolt Came home from the hospital in it & mine ever since. 1966 Catalina Ventura 2-door fastback 389/TH400

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