Myth or not? TH400 Tranny in our trucks - The 1947 - Present Chevrolet & GMC Truck Message Board Network

toms68cst · 03-29-2004, 07:20 PM

I’ve heard may folks here claim they have a factory TH400 transmission. I have the 68 resto pack and a lot of sales literature for our series of trucks. Nowhere is there any mention of any automatics other than the Powerglide or Turbo-Hydromatic. (I presume they are talking about the TH350.)

Was the TH400 really offered in these trucks or is it a myth? Who here can prove that they have a true FACTORY TH400 equipped truck and not the just a TH350 equipped truck? Did GM differentiate between the two automatics in their literature? What was the first year of the TH400? Was it available in all Light duty trucks or just the H.D. C/20’s and C/30’s?

I’ve been wondering about this for a while.

ckhd · 03-29-2004, 07:24 PM

Absolutely fact. If you had a big block (396 or 400/402) and a "Turbohydromatic", it was a TH400.

ckhd · 03-29-2004, 07:25 PM

Oh, that's the designation of the TH350 and the TH400.

TH350 = TurboHydramatic for a 350cu in engine
Th400 = TurboHydramatic for a 400 (396/402) cu in engine.

junkyardjohn · 03-29-2004, 07:30 PM

G.M. NEVER PUT A T-350 BEHIND A BIG BLOCK. EVERY FACTORY AUTOMATIC BEHIND A BIG BLOCK WAS A T-400.

JOHN

**COBALT** · 03-29-2004, 07:35 PM

Even without a truck you can verify this with the aluminum rivited tag on the side of the TH400 case. I have three TH400 transmissions (one in the truck which is original). All 3 of them belong to Chevy Trucks.

*67Fleetsidedream* · 03-29-2004, 07:35 PM

ckhd is right on the money.

**Canadian694x4** · 03-29-2004, 07:45 PM

so 68 was the first year for the TH400?

68 Suburban · 03-29-2004, 08:00 PM

Quote:

Originally posted by ckhd
Oh, that's the designation of the TH350 and the TH400.

TH350 = TurboHydramatic for a 350cu in engine
Th400 = TurboHydramatic for a 400 (396/402) cu in engine.

On my 68

TH400= Turbohydramatic for a 327ci engine.

Not only is it a turbo 400, but I was told by the trans rebuild guy that is the very desirable one that has the straight cut gears? I guess they were used on Motorhomes and heavy duty trucks too?

JON67 · 03-29-2004, 08:07 PM

my 67 has a th400 and the 327 engine. I believe it designates the turbo 400 on the tag in the glove box

**COBALT** · 03-29-2004, 08:11 PM

Typically it doesn't say that on the option sheet. It'll say "Turbohydromatic" or "Powerglide". The only way to be sure is to see if you still have your build sheet under the seat or behind the seat in front of the fuel tank. I don't know for sure if there was a TH400 for a chevy truck in 67. The only TH400s I've seen are for '69 and up.

TH400s were originally produced in 1965. The issue is just whether or not they made it into our trucks by 67.

Bill72BB · 03-29-2004, 08:18 PM

Here is what my Option sheet shows but I have a BB.
The 72 restoration guide shows 2 auto trans under that option ,one for the BB and another for without BB .?
There is also a 10 dollar difference in price .

Faster_than_you · 03-29-2004, 08:28 PM

it is elementary my dear watson, indeed there was a factory th400 setup for our trucks. I know this due to the fact that the cab floors had a larger tranny "hump" so when your ordering carpets say you had the factory th350. I said that I had a 400, not knowing there was a difference, and recieved the wrong carpet kit.

**john** · 03-29-2004, 08:51 PM

I think 1966 was the first year for th400 in pickups. That was the first year for 327's and they were equipped with them. I bought one that year. John

Suicide-D · 03-29-2004, 09:08 PM

high hump, low hump is not 100% correct... this truck had a low hump and TH400 behind a 350. 72 Cheyenne that sacrificed itself so others could live.....

stelth2002 · 03-29-2004, 10:48 PM

I can put this myth to sleep. GM didnt make the t350 until the end of 1968. So 1969 was the first year for those. Everything before that had the turbo 400 or powerglide.

68 Suburban · 03-30-2004, 12:27 AM

Quote:

Originally posted by stelth2002
I can put this myth to sleep. GM didnt make the t350 until the end of 1968. So 1969 was the first year for those. Everything before that had the turbo 400 or powerglide.

From my understanding, this is correct.

toms68cst · 03-30-2004, 12:30 AM

Thanks for the info. I've always wondered about the TH350 vs TH400 option in these trucks.

So.... In conclusion,

The TH350 came out AFTER the TH400 in 69?

Any "Turboautomatics" in 67-68 (and before) were TH400's?

Glove box option sheets don't list the TH350 or TH400 as different options just the "Turbohydromatic"option?

GENERALLY Turboautomatics after 68 were either TH 350 if mated to a SB/I6 and a TH400 if Mated to a BB?

I just always found it odd that in 68 anyway they go to great lenghs to explain availability of various manual trannys with various engines but they only mention ONE turbohydromatic transmission. I always thought the TH350 came first.

fearnoevo · 03-30-2004, 12:33 AM

a little known fact, the th400 takes around 35-40 hp more than the th350 to turn the pump.

Jay

***Josh*** · 03-30-2004, 12:37 AM

Some early to mid year 69s also recieved the TH400 in a half-ton with lwo hump cab, my 69 has factory TH400, and I've seen several others.

*Gee_Emm* · 03-30-2004, 12:40 AM

69 3/4 ton Custom Camper with 350/400 here

badpeanut · 03-30-2004, 01:05 AM

I don't mean to hijack the post, but there weren't ever any TH400s in the 4x4s (all automatic trucks were TH350s)?

68 Suburban · 03-30-2004, 01:17 AM

Quote:

Originally posted by fearnoevo
a little known fact, the th400 takes around 35-40 hp more than the th350 to turn the pump.

Jay

I think the figures I have heard is more like 15hp.

68 Suburban · 03-30-2004, 01:18 AM

Quote:

Originally posted by Faster_than_you
it is elementary my dear watson, indeed there was a factory th400 setup for our trucks. I know this due to the fact that the cab floors had a larger tranny "hump" so when your ordering carpets say you had the factory th350. I said that I had a 400, not knowing there was a difference, and recieved the wrong carpet kit.

My burb is a low hump turbo 400.

Duallie · 03-30-2004, 01:28 AM

THM400's came out in 1964 and were changed very slightly for 1965. THM350's came out in 1969, don't know what month.

Longhorn Man · 03-30-2004, 01:41 AM

I have never seen a small block?th400 truck with the high hump. The only time I have seen high humps over TH400s was big block trucks, and now 2 V-6 trucks, but only in 1/2 ton. (Finally able to explain the high hump in my GMC)

03-29-2004, 07:20 PM	#1
toms68cst Registered User Join Date: Jun 2000 Location: Bismarck, ND Posts: 4,286	Myth or not? TH400 Tranny in our trucks I’ve heard may folks here claim they have a factory TH400 transmission. I have the 68 resto pack and a lot of sales literature for our series of trucks. Nowhere is there any mention of any automatics other than the Powerglide or Turbo-Hydromatic. (I presume they are talking about the TH350.) Was the TH400 really offered in these trucks or is it a myth? Who here can prove that they have a true FACTORY TH400 equipped truck and not the just a TH350 equipped truck? Did GM differentiate between the two automatics in their literature? What was the first year of the TH400? Was it available in all Light duty trucks or just the H.D. C/20’s and C/30’s? I’ve been wondering about this for a while. __________________ Unrestored 68 C-10 CST. Original 327. 4-Speed CH465. 50k or so miles. TREASURER, Drum Brake Club. Last edited by toms68cst; 03-29-2004 at 07:22 PM.

03-29-2004, 07:24 PM	#2
ckhd Registered User Join Date: Oct 2000 Location: St. Johns, Arizona Posts: 2,660	Absolutely fact. If you had a big block (396 or 400/402) and a "Turbohydromatic", it was a TH400. __________________ my 2¢ - t.i.o.l.i. Bowen 1968 K20 fleet 1969 K10 swb fleet 1972 K10 Suburban 1972 C10 lwb step 1992 K1500 'burb 1995 K2500 'burb 1997 C1500 'burb 1999 K1500 2000 K1500 'burb Why do I own so many Suburbans?

03-29-2004, 07:25 PM	#3
ckhd Registered User Join Date: Oct 2000 Location: St. Johns, Arizona Posts: 2,660	Oh, that's the designation of the TH350 and the TH400. TH350 = TurboHydramatic for a 350cu in engine Th400 = TurboHydramatic for a 400 (396/402) cu in engine. __________________ my 2¢ - t.i.o.l.i. Bowen 1968 K20 fleet 1969 K10 swb fleet 1972 K10 Suburban 1972 C10 lwb step 1992 K1500 'burb 1995 K2500 'burb 1997 C1500 'burb 1999 K1500 2000 K1500 'burb Why do I own so many Suburbans?

03-29-2004, 07:30 PM	#4
junkyardjohn Registered User Join Date: Aug 2001 Location: SOMERSET KY. Posts: 6,427	G.M. NEVER PUT A T-350 BEHIND A BIG BLOCK. EVERY FACTORY AUTOMATIC BEHIND A BIG BLOCK WAS A T-400. JOHN __________________ junkyardjohn 69 1 TON TOW TRUCK // 84 4WD CUCV BLAZER// 85 1 TON 4WD STAKE TRUCK// 86 M1031 5/4 TON 4WD CUCV// ALOT OF OLD TRUCKS FOR ONE OLD MAN TO DRIVE. THERES ROOM FOR ALL OF GODS CREATURES RIGHT NEXT TO MY MASHED POTATOES// LIFE MEMBER OF P.E.T.A (PEOPLE EATING TASTY ANIMALS) DON'T RENT U-HAUL ALWAYS TELL THE TRUTH IT WILL AMAZE PART OF THE PEOPLE & ASTONISH THE REST

03-29-2004, 07:35 PM	#5
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	Even without a truck you can verify this with the aluminum rivited tag on the side of the TH400 case. I have three TH400 transmissions (one in the truck which is original). All 3 of them belong to Chevy Trucks. __________________ '69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA.

03-29-2004, 07:35 PM	#6
67Fleetsidedream Wiseass secured himself a BAN Join Date: Nov 2000 Location: MOON!!! Posts: 2,282	ckhd is right on the money.

03-29-2004, 07:45 PM	#7
Canadian694x4 Born To Lose Club Join Date: Feb 2003 Location: Calgary, Alberta/Oxenden, Ontario, Great White North Posts: 13,308	so 68 was the first year for the TH400? __________________ Brian Smith - "Born To Lose" 1969 Chevrolet K10 LWB Fleetside - Proud Owner For 22 Yrs - 1 of 208 Built & Sold In Canada!- 283 V8/350TH/NP208, 2" All Spring Lift, 32" Good Year MT/R's. 1972 GMC K2500 Custom LWB Fleetside - Proud Owner For 3 Yrs - 1 of 571 Built & Sold In Canada! - 350 V8/SM465/NP205, 4” Rough Country Lift, 33” Interco TSL Thornbirds 2007.5 GMC Sierra SLE 2500HD 4x4 - Proud Owner For 17 Yrs- 6.6L V8 Duramax Diesel/Allison 1000, 2" Lift, 33" Mickey Thompson MTZ's. 2008 Yamaha Raptor 700r - Proud Owner For 15 Yrs - ITP Mud Lites. 2015 John Deere 1025R - Proud Owner For 8 Yrs - 24HP Diesel/H120/54D/260B/SB1154.

03-29-2004, 08:07 PM	#9
JON67 Lootie Stole My Truck Join Date: May 2001 Location: Mountlake Terrace WA USA Posts: 822	my 67 has a th400 and the 327 engine. I believe it designates the turbo 400 on the tag in the glove box

03-29-2004, 08:11 PM	#10
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	Typically it doesn't say that on the option sheet. It'll say "Turbohydromatic" or "Powerglide". The only way to be sure is to see if you still have your build sheet under the seat or behind the seat in front of the fuel tank. I don't know for sure if there was a TH400 for a chevy truck in 67. The only TH400s I've seen are for '69 and up. TH400s were originally produced in 1965. The issue is just whether or not they made it into our trucks by 67. __________________ '69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA.

03-29-2004, 08:18 PM	#11
Bill72BB Thats the Hillbilly way Join Date: Jul 2001 Location: Torrance,Ca Posts: 5,980	Here is what my Option sheet shows but I have a BB. The 72 restoration guide shows 2 auto trans under that option ,one for the BB and another for without BB .? There is also a 10 dollar difference in price . Attached Images __________________ BILL Torrance Calif 90504 Member DUF Club Member Old Farts Club 72 3/4ton Custom Camper BB402/400 trans Dynomax Cerama-coat headers , Hei distributor ,Edelbrock 1411 air,ps,pb,leafsprings ,98 chevy 60/40 seat,S10 shoulder belts tilt,3.54 Dana 60 rear. 16" Eagle wheels with LT265/75 16 tires,Gaylord Lid,H4 headlights with 100W relay conversion. " If I knew I was going to live this long I would have taken better care of myself " Marriage changes passion...suddenly you're in bed with a relative. A GUY'S PRAYER.... Lord, I pray for a nympho with huge boobs who owns a liquor store and likes to fish and hunt and has a Harley .Amen ,

03-29-2004, 08:28 PM	#12
Faster_than_you Registered User Join Date: Mar 2004 Location: Virginia beach, Va Posts: 209	it is elementary my dear watson, indeed there was a factory th400 setup for our trucks. I know this due to the fact that the cab floors had a larger tranny "hump" so when your ordering carpets say you had the factory th350. I said that I had a 400, not knowing there was a difference, and recieved the wrong carpet kit. __________________ ~Christopher L. Orr 71 c20, 454- Stolen While Deployed. dynoed at 550 ft lbs, 425 hp at 3000 rpm (mustang dyno). TH400 3500 stall.... etc, etc.

03-29-2004, 08:51 PM	#13
john member #16 Join Date: Dec 1999 Location: Yuba City Ca. Posts: 3,618	I think 1966 was the first year for th400 in pickups. That was the first year for 327's and they were equipped with them. I bought one that year. John __________________ john http://67-72chevytrucks.com/vboard/showgroups.php board vendors http://www.flickr.com/photos/1745471...7602865984234/

03-29-2004, 09:08 PM	#14
Suicide-D Registered User Join Date: Jan 2001 Location: Katy, TX...but the love of my life resides in Dublin,OH. Posts: 1,408	high hump, low hump is not 100% correct... this truck had a low hump and TH400 behind a 350. 72 Cheyenne that sacrificed itself so others could live..... Attached Images

03-29-2004, 10:48 PM	#15
stelth2002 Young Gun wth Fast Inline Join Date: Jan 2002 Location: Idaho Posts: 1,475	I can put this myth to sleep. GM didnt make the t350 until the end of 1968. So 1969 was the first year for those. Everything before that had the turbo 400 or powerglide. __________________ 1967 Chevrolet LWB with built 292! 415 ft. lbs of torque, 4 speed :O with 27% overdrive too, 3.73 Posi. Frame and body done... getting painted!!!

03-30-2004, 12:30 AM	#17
toms68cst Registered User Join Date: Jun 2000 Location: Bismarck, ND Posts: 4,286	Thanks for the info. I've always wondered about the TH350 vs TH400 option in these trucks. So.... In conclusion, The TH350 came out AFTER the TH400 in 69? Any "Turboautomatics" in 67-68 (and before) were TH400's? Glove box option sheets don't list the TH350 or TH400 as different options just the "Turbohydromatic"option? GENERALLY Turboautomatics after 68 were either TH 350 if mated to a SB/I6 and a TH400 if Mated to a BB? I just always found it odd that in 68 anyway they go to great lenghs to explain availability of various manual trannys with various engines but they only mention ONE turbohydromatic transmission. I always thought the TH350 came first. __________________ Unrestored 68 C-10 CST. Original 327. 4-Speed CH465. 50k or so miles. TREASURER, Drum Brake Club.



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03-30-2004, 12:33 AM	#18
fearnoevo Registered User Join Date: Mar 2004 Posts: 68	a little known fact, the th400 takes around 35-40 hp more than the th350 to turn the pump. Jay

03-30-2004, 12:37 AM	#19
*Josh* He's got mean nasty FANGS! Join Date: Dec 1999 Location: Rockwell, NC Posts: 6,510	Some early to mid year 69s also recieved the TH400 in a half-ton with lwo hump cab, my 69 has factory TH400, and I've seen several others. __________________ 2004 K2500 Burb 1999 C3500 1985 Cutlass Supreme 1969 C-10 1967 C-10 Panel josh@67-72chevytrucks.com

03-30-2004, 12:40 AM	#20
Gee_Emm Account Suspended Join Date: Sep 2000 Posts: 4,002	69 3/4 ton Custom Camper with 350/400 here

03-30-2004, 01:05 AM	#21
badpeanut Not a bad nut after all.. Join Date: Dec 2000 Location: ND Posts: 1,756	I don't mean to hijack the post, but there weren't ever any TH400s in the 4x4s (all automatic trucks were TH350s)?

03-30-2004, 01:28 AM	#24
Duallie Registered User Join Date: Feb 2001 Location: Nikiski, Alaska Posts: 477	THM400's came out in 1964 and were changed very slightly for 1965. THM350's came out in 1969, don't know what month.

03-30-2004, 01:41 AM	#25
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	I have never seen a small block?th400 truck with the high hump. The only time I have seen high humps over TH400s was big block trucks, and now 2 V-6 trucks, but only in 1/2 ton. (Finally able to explain the high hump in my GMC)

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