350 In place of 700R4? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

74CustomK20 · 05-05-2016, 11:49 AM

Anyone ever do this swap? I couldn't find much on the search bar, but might be typing it wrong. Mostly found 350 vs 400... anyway I have a 1990 Sierra 4x4, and we have went through 3 700r4's. The original, and now 2 replacements. I pulled a turbo 350,out of my 73 k10 with a np203, and was curious how much, and what, it takes to put into the 1990?

**Mr_Rich** · 05-05-2016, 01:26 PM

Right off the bat I can tell you that you'll have to use SAE vs. metric bolts in place of what was used on the 700R4. You'll also have to move the trans mount since the length is closer to a 400 vs. 350. I had thoughts of using a 700R4 in place of a 350 in my old car at one time so I have a general idea of whats needed. That projects still pending since completion of my other two retirement projects.

74CustomK20 · 05-05-2016, 02:23 PM

I figured on redrilling a couple crossmember mount holes in the frame, so no worry there. And as far as sae-metric bolts I did account for that too. I'm mostly curious as to mounting the 241C to the T350 is my main concer.

74CustomK20 · 05-08-2016, 02:49 PM

Update. The th350 has about 1" sticking out past the end if the case, and the 700r4 has about 2-7/8" sticking out. How'd anyone fix this? Opinions sugestions?

**Palf70Step** · 05-08-2016, 05:43 PM

If you haven't, you might want to ask this question is the 4x4 section..lot more of those 0ff-road guys hanging out over there than what might be here. I am not aware of what goes where on any of the 4x4 setups on these trucks.

74CustomK20 · 05-08-2016, 07:21 PM

Thanks Palf, I might redo it over there.

Bigdav160 · 05-09-2016, 12:09 PM

You're going to have driveshaft length problems also.

Why don't you get a competent builder for the 700R4? There's very little strength difference between a TH350 and 700R4

mountie · 05-22-2016, 10:11 PM

Believe me, I know all about 700r4's failing.... I had over 10 repairs ( 6 rebuilds), before I found a builder that gave me a great transmission for the last 25 years!

I never abused my tranny..... stuff just broke!!

I went to California Performance Transmissions ( Huntington Beach, Ca.)

Formally Art Carr Transmission.... They gave me all the race / heavy duty parts.

My 700R4 is capable for a 650 HP engine...... In my stock '88 C2500.

Find a good builder and you will be fine.

05-05-2016, 11:49 AM	#1
74CustomK20 Registered User Join Date: Oct 2014 Location: Tell City, IN Posts: 637	350 In place of 700R4? Anyone ever do this swap? I couldn't find much on the search bar, but might be typing it wrong. Mostly found 350 vs 400... anyway I have a 1990 Sierra 4x4, and we have went through 3 700r4's. The original, and now 2 replacements. I pulled a turbo 350,out of my 73 k10 with a np203, and was curious how much, and what, it takes to put into the 1990? __________________ Big Nate Carp. Local 224. Buy made in the USA! 03 F350 6.0 Daily Race Truck. 79 C70 366 Project Dump.

05-05-2016, 01:26 PM	#2
Mr_Rich Registered User Join Date: May 2006 Location: Santa Maria, Calif. Posts: 781	Re: 350 In place of 700R4? Right off the bat I can tell you that you'll have to use SAE vs. metric bolts in place of what was used on the 700R4. You'll also have to move the trans mount since the length is closer to a 400 vs. 350. I had thoughts of using a 700R4 in place of a 350 in my old car at one time so I have a general idea of whats needed. That projects still pending since completion of my other two retirement projects. __________________ 1989 K1500 Chev. EC Original owner; some of the aftermarket parts I've installed are Borla headers, Hypertech chip, Edelbrock water pump, and a Stillen rear disc brake conversion kit. 2009 Hummer H3T 3.7L 5M (sold) 1997 K2500 Chev. EC 7.4L/ 4L80E 2018 Dodge Ram 2500 HD R/C

05-05-2016, 02:23 PM	#3
74CustomK20 Registered User Join Date: Oct 2014 Location: Tell City, IN Posts: 637	Re: 350 In place of 700R4? I figured on redrilling a couple crossmember mount holes in the frame, so no worry there. And as far as sae-metric bolts I did account for that too. I'm mostly curious as to mounting the 241C to the T350 is my main concer. __________________ Big Nate Carp. Local 224. Buy made in the USA! 03 F350 6.0 Daily Race Truck. 79 C70 366 Project Dump.

05-08-2016, 02:49 PM	#4
74CustomK20 Registered User Join Date: Oct 2014 Location: Tell City, IN Posts: 637	Re: 350 In place of 700R4? Update. The th350 has about 1" sticking out past the end if the case, and the 700r4 has about 2-7/8" sticking out. How'd anyone fix this? Opinions sugestions? __________________ Big Nate Carp. Local 224. Buy made in the USA! 03 F350 6.0 Daily Race Truck. 79 C70 366 Project Dump.

05-08-2016, 05:43 PM	#5
Palf70Step State of Confusion! Join Date: Jul 2002 Location: Gulfport, MS USA Posts: 46,611	Re: 350 In place of 700R4? If you haven't, you might want to ask this question is the 4x4 section..lot more of those 0ff-road guys hanging out over there than what might be here. I am not aware of what goes where on any of the 4x4 setups on these trucks. __________________ Bill 1970 Chevy Custom/10 LWB Fleetside 2010 Toyota Tacoma PreRunner SR5 Double Cab - DD Member of Louisiana Classic Truck Club (LCTC) Bill's Gallery Life isn't tied with a bow, but it's still a gift. Live simply. Love generously. Care deeply. Speak kindly. Leave the rest to God!

05-08-2016, 07:21 PM	#6
74CustomK20 Registered User Join Date: Oct 2014 Location: Tell City, IN Posts: 637	Re: 350 In place of 700R4? Thanks Palf, I might redo it over there. __________________ Big Nate Carp. Local 224. Buy made in the USA! 03 F350 6.0 Daily Race Truck. 79 C70 366 Project Dump.

05-09-2016, 12:09 PM	#7
Bigdav160 Registered User Join Date: Apr 2011 Location: Klein Texas Posts: 3,852	Re: 350 In place of 700R4? You're going to have driveshaft length problems also. Why don't you get a competent builder for the 700R4? There's very little strength difference between a TH350 and 700R4 __________________ My Classics: '72 K20 Suburban + '65 Dodge Town Wagon '72 Corvette Roadster +'67 Corvette Roadster '73 Z-28 Camaro '63 Ford SWB Uni Pickup '50 Ford Coupe

05-22-2016, 10:11 PM	#8
mountie Registered User Join Date: Jun 2011 Location: Bradenton, Fla. Posts: 1,100	Re: 350 In place of 700R4? Believe me, I know all about 700r4's failing.... I had over 10 repairs ( 6 rebuilds), before I found a builder that gave me a great transmission for the last 25 years! I never abused my tranny..... stuff just broke!! I went to California Performance Transmissions ( Huntington Beach, Ca.) Formally Art Carr Transmission.... They gave me all the race / heavy duty parts. My 700R4 is capable for a 650 HP engine...... In my stock '88 C2500. Find a good builder and you will be fine. __________________ '70 GTO Midnight Blue '88 GMC Sierra SLE 392,000 miles-(2018) sold to Classic car shop in Germany. '93 Cadillac STS Black '93 Mercedes SL 500 Teal '86 Yamaha FZ750 - 15,000 RPM '86 Yamaha FJ1200 - Criminally Fast 2016 Ferrari 488 GTB, I drive it - don't own it. '05 GMC Yukon XL , SLT 4wd ( just purchased 2018)



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