Have a 79 k10, just bought an 81. Help with swap?

sticman said:

Holy wow.... You wont see your combo any time soon.

If a original gm release very rare. Three in the tree made your 4x4 unique.
Coming out of the 70's the three in the tree option was so unpopular.

Looks like a Ford top-loader crazy. Broncos are rumored to have come with a top-loaders as well.
Most ford top-loaders are only 2wd just like the GM saginaw's.
All common GM 3 speed manuals have side bolt on covers.

Got to love hecho en México = made in Mexico
I suspect 2603435 is the part number and F.02.78 the date code.
You'll have to go to a dealer and get a build sheet to find out what you got if your interested in knowing more. Guaranteed the dealer parts guy is going to wish you never walked in.

Gm did some different stuff if you ordered a truck with 3 speed on the column such as the offering of the dana 20 as an option when combo-ed with 3 in the tree. Rumor has it for years 69 to 74 you could get a combo of saginaw 3 speed coupled to dana 20 for GM.

Thanks for sharing... Cool GM things to see and learn.

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Yep definitely a rare combination! I'm still stunned to find a top-loader in front of a chevrolet-coded np208, and behind an i6 250, since that's the motor that came out of this truck. What are the chances of a small block Chevy motor bolting up to this trans?

Is the bolt pattern on the i6 250 and a 350 the same? and will the clutch and flywheel from the i6 work on the 350? My 350 already has a pilot bearing installed in the crank, even thought its being used with a th350.

I was originally leaning towards swapping the 350 + th350 + np203 into the 81, mostly because of reading about the saginaw 3 speeds being fairly weak, but if this is a 3 speed ford top-loader it is very very strong, much stronger than a saginaw 3 speed. Also what are the chances of fitting an np205 or my np203 to this mystery combination? Would it be the same NP208 thats behind any other 81 k10, or something totally unique to this setup?

thanks for the help, and glad to share this unique combination.

Ok I have several things to say..

1. Where in NC are you, may have to see this in person.
2. You need to clean off the flat spot at the 4 o clock position below "hecho en mexico". That is most definitely a stamping pad for ID numbers of some sort.
3. It could be a toploader imposter. Check this out, looks like your trans. http://www.davidkeetoploaders.com/imposters.htm Look specifically at the last picture on the bottom.
Also, check that site for 3 speed ID numbers and look on yours..if somehow it is a Ford trans.
4. They did make a 250 cu-in FORD straight six. Someway, somehow somebody could have put that in along with a ford trans. Might explain the crude hole in the floor. You could have originally had something different.
5. Your blurry pic of the engine bay and steering column doesn't convince me that it was originally "3 on the tree". Looks more like it was an automatic column, and the fact that there is a selector window on the gauge cluster. Take some better pics of the other side of the column and selector window. Also a closer, better pic of the column coming out of the firewall.

Boone83K10 said:

Ok I have several things to say..

1. Where in NC are you, may have to see this in person.
2. You need to clean off the flat spot at the 4 o clock position below "hecho en mexico". That is most definitely a stamping pad for ID numbers of some sort.
3. It could be a toploader imposter. Check this out, looks like your trans. http://www.davidkeetoploaders.com/imposters.htm Look specifically at the last picture on the bottom.
Also, check that site for 3 speed ID numbers and look on yours..if somehow it is a Ford trans.
4. They did make a 250 cu-in FORD straight six. Someway, somehow somebody could have put that in along with a ford trans. Might explain the crude hole in the floor. You could have originally had something different.
5. Your blurry pic of the engine bay and steering column doesn't convince me that it was originally "3 on the tree". Looks more like it was an automatic column, and the fact that there is a selector window on the gauge cluster. Take some better pics of the other side of the column and selector window. Also a closer, better pic of the column coming out of the firewall.

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1) Morganton/Hickory area. The truck hasn't been towed to my place yet, but feel free to come take a look at it sometime after i get it towed. I'm stumped by the truck.

3) Ive been researching this for hours and hours...it appears the "imposters" were only versions of the 4 speed (3 speed with 4th gear OD). Notice in the pics in the link, the transmission has 3 shifter bolts/levers coming from the side. The original top-loader 3 speed and the transmission in my truck has only 2. From what I've learned, there was never an imposter of the standard 3 speed. Although I'm confused about the "Hecho en Mexico." Ive read about some older ford engines having "Hecho en Mexico" stamped in them, but don't know about the transmissions.

4) Looking at the bell housing, its definitely for a Chevrolet. Same exact pattern as the TH350 in my 79.

5) I had machining class with the guy that i got it from, he drove it to school, and it was column-shifted at the time. Hes the one that converted it to floor shifter, I was in the shop when he was machining the brackets for the floor shifter mechanism.

Also i found one other example of one of these transmissions in a Chevrolet. The guy claims it came from a 76 4x4 Blazer. He lists it as a Saginaw 3-speed, but that's not what it is. http://www.pirate4x4.com/forum/engi...inaw-3-speed-colum-shift-tranny-se-kanas.html

well I have wasted my friday at work looking up stuff on this.


I think it's a saginaw, but a weird one that doesn't have a side cover. saw some vids on this exact setup, but they were all C10... not a K10.

Boone83K10 said:

well I have wasted my friday at work looking up stuff on this.


I think it's a saginaw, but a weird one that doesn't have a side cover. saw some vids on this exact setup, but they were all C10... not a K10.

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I might start a thread specifically about this topic, the possibilities of having a ford 3.03 in a Chevrolet 4x4, see if anyone else has heard of it...Ide think the only way it would be a Saginaw is if the guts (gearsets themselves) were made by saginaw, because the case is just too similar to a ford 3.03 to be coincidental.

I know that the HD 3 speed was an option back in old Pontiacs, and was the same exact ford 3.03 transmission, but that was in a 2wd car..never heard of such thing in a 4x4 truck.

EDIT: Well, i believe this mystery transmission is a Tremec T-160. A rare combo, but it was offered by GM. Check out these links.
http://www.drivetrain.com/parts_cat...verhaul_kits/tremec_3_speed_overhaul_kit.html
http://www.chevytalk.org/fusionbb/showtopic.php?tid/60294/

the 2nd link mentions this transmission being used 1967-1981, but mostly in 3/4 ton and bigger. "Description: Cast iron, top-loaded case with side shift linkage. Fully synchronized with 36 tooth synchro rings. Same unit as Ford RAT except for a G.M. bolt pattern to the bellhousing. Has R28-20-15 cluster gear. Found in heavy-duty applications."

"it is a top access with side mounted shifting. It was used in 4 x 4 trucks..."

DOUBLE EDIT: Is DEFINITELY a Tremec T160. From drivetrain.com "This transmission series has a casting number of 260XXXX." the transmission in this truck has casting number 2603435.

Hate to revive a thread this old, but while looking for some info on a truck I got last year, I discovered it was THIS truck. If anyone is till on here that may have specific info on this truck (engine work done, etc), please contact me.

I'm glad you brought this thread back up, I had forgotten all about this gem. So does the truck still have the neato 3-speed or does it have an auto swapped in now?

ToStill has the 3 speed, I was under the impression it was a Saginaw. Looking to change it out in the future, possibly for a 5 speed. Having trouble with it staying in 1st without throttle pressure. That is the only reason I happened across this thread. Hoping OP will see, would like some info on the 350 engine in it.

amorgan93 said:

DOUBLE EDIT: Is DEFINITELY a Tremec T160. From drivetrain.com "This transmission series has a casting number of 260XXXX." the transmission in this truck has casting number 2603435.

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2.99, 1.75, 1.00, 3.17

Back in the 60s GM used Dearborn transmissions in the GTO. Dearborn was code for Ford, GM Didn't have a 3 speed tough enough for the Pontiac engine. I wonder if it's the same kind of deal. I've never heard of it,but they did it once ,maybe they did it again.

Ricko1966 said:

Back in the 60s GM used Dearborn transmissions in the GTO. Dearborn was code for Ford GM Didn't have a 3 speed tough enough for the Pontiac engine. I wonder if it's the same kind of deal. I've never heard of it,but they did it once m,maybe they did it again.

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And in the 70's there were Lincolns with GM A/C and power steering pumps. Manufacturers make curious decisions sometimes.

bucket said:

And in the 70's there were Lincolns with GM A/C and power steering pumps. Manufacturers make curious decisions sometimes.

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And AMC didn't have anything made by AMC. It was all chevrochrysleford

Ricko1966 said:

And AMC didn't have anything made by AMC. It was all chevrochrysleford

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Well yeah, that goes without saying lol. All Makes Considered.