3spd to 350 tranny swap help? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

tattoo · 09-18-2005, 05:39 PM

I am taking out my three spd tranny and swapping it with a 350. Does any one know how the tranny will fit? or what mods i will have to do to the crossmembers or tranny mounts. theres nothing wrong with the three in the tree i would love to keep it for classic purposes but i am taking my truck across the country, all around the states and back to canada, and i think a 350 automatic is my best way to go. easy to come by parts, just incase i have to do a transmission repair when im halfway across the country from my shop.
can anyone help me with my 69 c-10 1/2ton questions?

thanxs
Anthony
Barrie Ont. Ca

JimKshortstep4x4 · 09-18-2005, 07:55 PM

It is a pretty straight forward swap. You will need an auto cross member for the tranny mount. I would remove the stick frame parts to get them out of the way. You will need the linkage and steering column. The driveshaft will work like it is.

Good luck.

Jim

da-burb · 09-18-2005, 09:46 PM

You have selected the perfect swap. The TH350 is the same length as your 3sp, same output spline count so your drive shaft is correct.

tattoo · 09-19-2005, 12:27 AM

thanks for your help guys

ChevyMex · 09-20-2005, 01:37 AM

My truck has a 4 speed and Reverse tranny, came from factory with a 292 Engine with a floor shifter, the engine is a 68 made in Mexico, at least is what the bottom of the block shows. Can i swap this tranny for a TH350?, what are the benefits?, gas milage?, performance?, what kind of transmission is the one i have right now?.

**truckdude239** · 10-06-2005, 09:06 AM

i have a friend that went from an 3 speed to an turbo 350 auto tran in her 67 c-10 we quicky found out that the rear end had to be regeared because it was red lining every gear because the rear end wasn't geared to the tranny

cdowns · 10-06-2005, 09:14 AM

Quote:

Originally Posted by da-burb

You have selected the perfect swap. The TH350 is the same length as your 3sp, same output spline count so your drive shaft is correct.

or you could use a 2004R tranny and have an overdrive with the same ease and ALOT better gas milage

**pjmoreland** · 10-06-2005, 11:34 AM

Board member Shifty recently removed his manual transmission crossmember and ran into some difficulties with removing the rivets. Here are some pictures of how he went about removing the crossmember:

http://satellitehead.com/gallery/thumbnails.php?album=4

I think he did a write-up on how he did this, but I can't find it.

cableguy0 · 10-06-2005, 11:39 AM

the 3spd and th350 have almost exactly the same gears.final drive is the same at 1-1

my68 · 04-05-2012, 11:20 PM

I know this is about 6 yrs to late....I just bought a 68c15 long box. Some one put in a 350 with a 4spd manual. is the 4spd longer than a 3spd? Will my drive line work with the th350 with out mod's. When they put it in they just rested the tranny on the existing cross member with no rubber mount and didn't even bolt it down. Glad to see the post from pjmoreland on the cross member removal. Only I will have to do it with engine in. I will start a build tread here soon. Wont be real active at first. But I do have a bunch of picture.

09-18-2005, 05:39 PM	#1
tattoo "Bondo, just say no!" Join Date: Sep 2005 Location: Barrie Ontario Canada Posts: 75	3spd to 350 tranny swap help? I am taking out my three spd tranny and swapping it with a 350. Does any one know how the tranny will fit? or what mods i will have to do to the crossmembers or tranny mounts. theres nothing wrong with the three in the tree i would love to keep it for classic purposes but i am taking my truck across the country, all around the states and back to canada, and i think a 350 automatic is my best way to go. easy to come by parts, just incase i have to do a transmission repair when im halfway across the country from my shop. can anyone help me with my 69 c-10 1/2ton questions? thanxs Anthony Barrie Ont. Ca Last edited by tattoo; 09-18-2005 at 05:40 PM.

09-18-2005, 09:46 PM	#3
da-burb "Ochre Ogre" Join Date: Apr 2000 Location: Springfield, MN Posts: 3,558	You have selected the perfect swap. The TH350 is the same length as your 3sp, same output spline count so your drive shaft is correct. __________________ Bowtie Truck Stop Inc. Mid-West GM Truck Restoration Parts Supplier Your Key Parts, Auto Metal Direct, Dynacorn, and Goodmark dealer. like us @ www.facebook.com/BowtieTruckStop 1971 C-10 Suburban (Ochre) 1971 K-10 Suburban (Ochre) 1972 C-10 Suburban (Ochre) 1972 K-20 Suburban (Yellow- that just aint right!) Springfield, Minnesota 56087

10-06-2005, 11:39 AM	#9
cableguy0 Senior Member Join Date: Apr 2000 Location: Delta,Pa Posts: 14,950	the 3spd and th350 have almost exactly the same gears.final drive is the same at 1-1 __________________ Owner of North Point Car Care in Dundalk Md. We specialize in custom exhaust on both modern and classic vehicles. We are a full service auto shop from classics to modern vehicles. Feel free to contact me with questions. I will give a 10% discount to any board member.

04-05-2012, 11:20 PM	#10
my68 Registered User Join Date: Mar 2012 Location: Emmett Posts: 2	Re: 3spd to 350 tranny swap help? I know this is about 6 yrs to late....I just bought a 68c15 long box. Some one put in a 350 with a 4spd manual. is the 4spd longer than a 3spd? Will my drive line work with the th350 with out mod's. When they put it in they just rested the tranny on the existing cross member with no rubber mount and didn't even bolt it down. Glad to see the post from pjmoreland on the cross member removal. Only I will have to do it with engine in. I will start a build tread here soon. Wont be real active at first. But I do have a bunch of picture.

09-18-2005, 07:55 PM	#2
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	It is a pretty straight forward swap. You will need an auto cross member for the tranny mount. I would remove the stick frame parts to get them out of the way. You will need the linkage and steering column. The driveshaft will work like it is. Good luck. Jim

09-19-2005, 12:27 AM	#4
tattoo "Bondo, just say no!" Join Date: Sep 2005 Location: Barrie Ontario Canada Posts: 75	thanks for your help guys

09-20-2005, 01:37 AM	#5
ChevyMex Registered User Join Date: Jul 2005 Location: Mexico Posts: 92	My truck has a 4 speed and Reverse tranny, came from factory with a 292 Engine with a floor shifter, the engine is a 68 made in Mexico, at least is what the bottom of the block shows. Can i swap this tranny for a TH350?, what are the benefits?, gas milage?, performance?, what kind of transmission is the one i have right now?.

10-06-2005, 09:06 AM	#6
truckdude239 Senior Member Join Date: Sep 2005 Location: Lewisville, Nc Posts: 10,230	i have a friend that went from an 3 speed to an turbo 350 auto tran in her 67 c-10 we quicky found out that the rear end had to be regeared because it was red lining every gear because the rear end wasn't geared to the tranny

10-06-2005, 11:34 AM	#8
pjmoreland Senior Member Join Date: Jan 2005 Location: CA Posts: 5,394	Board member Shifty recently removed his manual transmission crossmember and ran into some difficulties with removing the rivets. Here are some pictures of how he went about removing the crossmember: http://satellitehead.com/gallery/thumbnails.php?album=4 I think he did a write-up on how he did this, but I can't find it.



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