1977 K20 Trannys - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Fletch · 11-30-2003, 08:55 PM

Any of you 'old timers' out there remember what automatic transmission came with the 1977 3/4 ton 400 cu.in. Chevy 4x4 pickup trucks with the NP205 Full time four wheeldrive. I want to settle an argument with a friend, he said you could get a THM 400 with that truck. I remember the THM 350 was the only tranny that came with full time fourwheel drive, no matter what . What say you guys?

*mike reeh* · 11-30-2003, 09:55 PM

If it is the NP205, its a part time truck.. The NP203 was fulltime and would have been a TH350 trans behind it, in 1977.... In other years you could get a th400 and in '74 you could even get a SM465 3spd manual on the full time 4x4...

Bottom line is that it is possible to find/build a full-time (np203) with a th400, they are uncommon though...

as for 1977 strictly, I dont think you could have gotten a th400/np203 combo because Ive never seen or heard of one.. But thats not fact. I think I have some brochures somewhere, or you could look at that one brochures site that grim reaper always posts..

mike

Fletch · 11-30-2003, 11:21 PM

Thanks Mike, I know my memory is a little fuzzy after 26yrs. I thought full time 4wheel drive was the NP205. But I do remember that I could not order the THM 400 in that truck, I went to several different Dealers. My friend insists he had one in his '77.
Thanks again.

*mike reeh* · 12-01-2003, 01:47 AM

another thing that popped into my head since you mentioned special ordering, was I went to look at a parts truck at this guys house and the truck was a '78 K20 that the guy special ordered from the factory, with a th400 and full time 4x4... The truck was in parts and he told me it was a th400.. looking thru the shed, I saw the t-case and knew it was a NP203, and so I say "are you SURE its a th400?" he says yes, he had to special order it.. I looked at the T-case adapter and sure enough it had the 6-bolt hexagonal pattern. So the general MADE em but I dont think they mass produced em for the normal dealer shipments.

On a side note, that setup is actually quite desireable to some parts seekers because the NP203+th400 adapter can be used to build a dual transfer case setup that would bolt to a TH400...... a TH400+NP203gearbox+NP205 would be about as bulletproof as you could get...

enough rambling.. hope this enlightened you some

mike

77bowtie · 12-01-2003, 10:46 AM

In 77 with a 400cid engine the trany is a TH-400, For sure my Bonanza came that way!

Fletch · 12-01-2003, 03:42 PM

Quote:

Originally posted by 77bowtie
In 77 with a 400cid engine the trany is a TH-400, For sure my Bonanza came that way!

Boy, I must be getting old, I don't remember the Bonanza, was that a 4x4 Pick-up? Did you special order it with the THM 400?

Fletch · 12-01-2003, 03:49 PM

Quote:

Originally posted by mike reeh

enough rambling.. hope this enlightened you some

mike

Ha! Me thinks I may have opened a can of worms!

77bowtie · 12-02-2003, 12:46 PM

The Bonanza is/was a special promotional package. I checked Chuck's Chevy Trucks and in 77 all 400/454 engine'd trucks came with a 4-core radiator and a TH-400 tranny.

77bowtie · 12-02-2003, 12:58 PM

Oh yeah...my 77 came with a np-203 tc too.

Devil'S Ride · 12-02-2003, 05:19 PM

My 77 originally had a 400 an 203/TH400....course, Im the third owner, an when I got it someone had swapped the Th400 for a TH350.....an the 400 SB for a 350.....so, as far as I know...it came with TH400 and NP203....

*mike reeh* · 12-02-2003, 11:19 PM

Quote:

Originally posted by 77bowtie
The Bonanza is/was a special promotional package. I checked Chuck's Chevy Trucks and in 77 all 400/454 engine'd trucks came with a 4-core radiator and a TH-400 tranny.

that is definately incorrect. my 77 K25 gmc was 400sb/th350/np203

mike

77bowtie · 12-03-2003, 11:59 AM

Perhaps, Mike, perhaps.

*mike reeh* · 12-04-2003, 03:02 AM

I think that different areas (geographically) will see major differences in what GM put out.. Especially being that Im in california.. I dont doubt for a minute that they made th400 full timers.. but I do know that in the several years Ive been into the 73-87 4x4s, (mainly 77), ive never seen a th400/np203 truck.. and ive seen a LOT of trucks.. with the exception of the '78 parts truck in my previous post. That, coupled with the fact that I have seen many (including my own unmolested) 77 th350/np203 K25, brings me to the conclusion that yes you get a th350 OR th400 full time 3/4ton pickup thru the years.. one may be more common than the other (depending on location?) but they were both available. were they both available in 77? maybe. in fact- probably. Is it unreasonable to say that you could ONLY get a th400/np203 in 1977? Yes =)

mike

*1FaastC10* · 12-04-2003, 08:49 AM

my uncle has a 79 K20 with a TH400/203 in it, and my grandpa had a 77 K20 with a TH350/205

77bowtie · 12-04-2003, 12:48 PM

Hey for enough $$$ GM could sell you a special order truck with GM electric diesel power. Look at all the CPO"S and the "muscle" cars of the 60's. I have found that not much is written in stone.

Fletch · 12-04-2003, 07:01 PM

Well I was reading through ChucksChevytrucks pages, and it said the Th350 was the only tranny available from '73 to '76. And the th400 were 'available' from '77 & later. So that means that 1977 was a transition year and possably early 1977's had the th350's & later models had th400's if you chose to order so. When buying my 1977 I decided to go with the 2wd for two reasons. Nicer ride and I wanted the 454/TH400 combo, wich I know for sure did not come in the 4x4's. I would have settled for the 400SB/TH400 in the 4x4 but was told it was not available, this was in Jan. of 1977. BTW, I still have this truck, it's all original. I stored it every winter. See signature.

TROYLV · 12-04-2003, 09:25 PM

got a 74 blazer with turbo 400 and 203 tc. it isn't a full removable top either. thought both were strange.

*1FaastC10* · 12-05-2003, 04:16 AM

Quote:

Originally posted by Fletch
Well I was reading through ChucksChevytrucks pages, and it said the Th350 was the only tranny available from '73 to '76.

consider your source. not very reliable information at all, as far as i can tell. one case that i can think of is the mention of the hood ornament being new for '86. that completely explains why the ragenrat has one, and 3 of the 81-83 trucks i have owned have had them. this was also verified trough GM parts catalogs, which list them back to '80. after that who knows, they're probably long discontinued.

Fletch · 12-05-2003, 03:53 PM

[QUOTE]Originally posted by 1FaastC10
[B]

consider your source. not very reliable information at all, as far as i can tell.

Yes, I agree as I noticed other discrepancies while reading through chuckscchevytrucks.

11-30-2003, 08:55 PM	#1
Fletch Registered User Join Date: Nov 2003 Location: Crabwell Corners Posts: 9	1977 K20 Trannys Any of you 'old timers' out there remember what automatic transmission came with the 1977 3/4 ton 400 cu.in. Chevy 4x4 pickup trucks with the NP205 Full time four wheeldrive. I want to settle an argument with a friend, he said you could get a THM 400 with that truck. I remember the THM 350 was the only tranny that came with full time fourwheel drive, no matter what . What say you guys?

12-02-2003, 05:19 PM	#10
Devil'S Ride Registered User Join Date: Nov 2003 Location: Grants PassOregon Posts: 335	My 77 originally had a 400 an 203/TH400....course, Im the third owner, an when I got it someone had swapped the Th400 for a TH350.....an the 400 SB for a 350.....so, as far as I know...it came with TH400 and NP203.... __________________ The Devil 1983 ONE TON 454/400/208 11" of lift on 44's

12-04-2003, 09:25 PM	#17
TROYLV Registered User Join Date: Oct 2002 Location: LAS VEGAS, NV. Posts: 157	400-203 got a 74 blazer with turbo 400 and 203 tc. it isn't a full removable top either. thought both were strange. __________________ troy wilson

11-30-2003, 09:55 PM	#2
mike reeh 5 day ban, learn to behave. Join Date: Nov 2002 Location: san diego, ca Posts: 683	If it is the NP205, its a part time truck.. The NP203 was fulltime and would have been a TH350 trans behind it, in 1977.... In other years you could get a th400 and in '74 you could even get a SM465 3spd manual on the full time 4x4... Bottom line is that it is possible to find/build a full-time (np203) with a th400, they are uncommon though... as for 1977 strictly, I dont think you could have gotten a th400/np203 combo because Ive never seen or heard of one.. But thats not fact. I think I have some brochures somewhere, or you could look at that one brochures site that grim reaper always posts.. mike

11-30-2003, 11:21 PM	#3
Fletch Registered User Join Date: Nov 2003 Location: Crabwell Corners Posts: 9	Thanks Mike, I know my memory is a little fuzzy after 26yrs. I thought full time 4wheel drive was the NP205. But I do remember that I could not order the THM 400 in that truck, I went to several different Dealers. My friend insists he had one in his '77. Thanks again.

12-01-2003, 01:47 AM	#4
mike reeh 5 day ban, learn to behave. Join Date: Nov 2002 Location: san diego, ca Posts: 683	another thing that popped into my head since you mentioned special ordering, was I went to look at a parts truck at this guys house and the truck was a '78 K20 that the guy special ordered from the factory, with a th400 and full time 4x4... The truck was in parts and he told me it was a th400.. looking thru the shed, I saw the t-case and knew it was a NP203, and so I say "are you SURE its a th400?" he says yes, he had to special order it.. I looked at the T-case adapter and sure enough it had the 6-bolt hexagonal pattern. So the general MADE em but I dont think they mass produced em for the normal dealer shipments. On a side note, that setup is actually quite desireable to some parts seekers because the NP203+th400 adapter can be used to build a dual transfer case setup that would bolt to a TH400...... a TH400+NP203gearbox+NP205 would be about as bulletproof as you could get... enough rambling.. hope this enlightened you some mike

12-01-2003, 10:46 AM	#5
77bowtie Registered User Join Date: Apr 2003 Location: New Mexico. Of all places for an Island boy. Posts: 180	In 77 with a 400cid engine the trany is a TH-400, For sure my Bonanza came that way!

12-02-2003, 12:46 PM	#8
77bowtie Registered User Join Date: Apr 2003 Location: New Mexico. Of all places for an Island boy. Posts: 180	The Bonanza is/was a special promotional package. I checked Chuck's Chevy Trucks and in 77 all 400/454 engine'd trucks came with a 4-core radiator and a TH-400 tranny.

12-02-2003, 12:58 PM	#9
77bowtie Registered User Join Date: Apr 2003 Location: New Mexico. Of all places for an Island boy. Posts: 180	Oh yeah...my 77 came with a np-203 tc too.

12-03-2003, 11:59 AM	#12
77bowtie Registered User Join Date: Apr 2003 Location: New Mexico. Of all places for an Island boy. Posts: 180	Perhaps, Mike, perhaps.

12-04-2003, 03:02 AM	#13
mike reeh 5 day ban, learn to behave. Join Date: Nov 2002 Location: san diego, ca Posts: 683	I think that different areas (geographically) will see major differences in what GM put out.. Especially being that Im in california.. I dont doubt for a minute that they made th400 full timers.. but I do know that in the several years Ive been into the 73-87 4x4s, (mainly 77), ive never seen a th400/np203 truck.. and ive seen a LOT of trucks.. with the exception of the '78 parts truck in my previous post. That, coupled with the fact that I have seen many (including my own unmolested) 77 th350/np203 K25, brings me to the conclusion that yes you get a th350 OR th400 full time 3/4ton pickup thru the years.. one may be more common than the other (depending on location?) but they were both available. were they both available in 77? maybe. in fact- probably. Is it unreasonable to say that you could ONLY get a th400/np203 in 1977? Yes =) mike

12-04-2003, 08:49 AM	#14
1FaastC10 Account Suspended Join Date: Oct 2002 Location: Elkhart, IN Posts: 6,399	my uncle has a 79 K20 with a TH400/203 in it, and my grandpa had a 77 K20 with a TH350/205

12-04-2003, 12:48 PM	#15
77bowtie Registered User Join Date: Apr 2003 Location: New Mexico. Of all places for an Island boy. Posts: 180	Hey for enough $$$ GM could sell you a special order truck with GM electric diesel power. Look at all the CPO"S and the "muscle" cars of the 60's. I have found that not much is written in stone.



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12-04-2003, 07:01 PM	#16
Fletch Registered User Join Date: Nov 2003 Location: Crabwell Corners Posts: 9	Well I was reading through ChucksChevytrucks pages, and it said the Th350 was the only tranny available from '73 to '76. And the th400 were 'available' from '77 & later. So that means that 1977 was a transition year and possably early 1977's had the th350's & later models had th400's if you chose to order so. When buying my 1977 I decided to go with the 2wd for two reasons. Nicer ride and I wanted the 454/TH400 combo, wich I know for sure did not come in the 4x4's. I would have settled for the 400SB/TH400 in the 4x4 but was told it was not available, this was in Jan. of 1977. BTW, I still have this truck, it's all original. I stored it every winter. See signature.

12-05-2003, 03:53 PM	#19
Fletch Registered User Join Date: Nov 2003 Location: Crabwell Corners Posts: 9	[QUOTE]Originally posted by 1FaastC10 [B] consider your source. not very reliable information at all, as far as i can tell. Yes, I agree as I noticed other discrepancies while reading through chuckscchevytrucks.

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