700 r4 in a K20? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**leddzepp** · 05-06-2019, 02:24 PM

I have a chance to pick up a 700r4 transmission for free, it is a non computer controlled unit. I’m not sure what it came out of originally but am wondering if I can use it in my 72 K20? Do I need a special 4x4 adapter to connect it to my np205 transfer case, or can I use the one from my th350 that’s already there? Thanks in advance.

57taskforce · 05-06-2019, 06:48 PM

There’s a few ways to skin this cat. The first is a shortened transmission output shaft that will then let you use the th350 adaptor to your 205. The second is a spacer that goes between the adaptor and the transmission that lets you keep the stock Kcase 700r4 output shaft. If your going to go thru the tranny use option 1. I looked into this a year or two back so this is just the gist of it. If I remember right you may have to move the motor forward because the 700r4 is longer than the th350. Don’t quote me on it though.

I was in your neck of the woods last month in my Camaro. The freeway can be pretty fun with 400hp and a 6 speed. If I was in my K20 with no overdrive, not so much. It’s not that I worry about the engine speed or anything like that, I just don’t care to go 80-90 in that beast.

**special-K** · 05-06-2019, 08:07 PM

Yes, you move engine forward so the transfer case stays in the same place so the driveshafts can go untouched.

**jocko** · 05-06-2019, 08:28 PM

If trans is a 2WD unit, need the shortened output shaft HERE

Original K-case is slightly stronger because of a 6-bolt torque converter cover, but unless you're going baja, probably not necessary.

Torque converter cover bolt holes may be a clue - I think if 2WD, there may only be 4(?) K-case had 6 I believe.

EDIT: I believe doing the output shaft swap and moving the engine fwd as Tim mentions is the preferred approach.

**leddzepp** · 05-06-2019, 08:49 PM

Sorry, I should have specified the 700 is a 2wd transmission. Thanks for the input so far everyone!

**Mts67C10K20** · 05-07-2019, 09:05 AM

Did this last year
All correct so far
You need an output shaft installed for a 4x4
You can use a stock one with advanced adapters , adapter
Or a modified shaft and a 350t adapter
Then move motor forward 2"
Also will need the presure cable and carb bracket and a lockup kit
There are many out there
Have fun
Having overdrive is the only way to go imo

Bigdav160 · 05-07-2019, 01:49 PM

I've done it too and used the AA output shaft.

Things I learned:
my factory 4x4 fan shroud no longer fit
the coolant hoses had to be modified
my A/C lines had to be modified
I had to move the shift linkage forward on the frame
I notched the front crossmember for crank pulley clearance
The transmission pan is really close to the front driveshaft but clears possibly because I have a 2" lift
The exhaust pipes had to be lengthened

Otherwise I would do it again

05-06-2019, 02:24 PM	#1
leddzepp Moderator Join Date: May 2007 Location: Southern Cal Posts: 19,994	700 r4 in a K20? I have a chance to pick up a 700r4 transmission for free, it is a non computer controlled unit. I’m not sure what it came out of originally but am wondering if I can use it in my 72 K20? Do I need a special 4x4 adapter to connect it to my np205 transfer case, or can I use the one from my th350 that’s already there? Thanks in advance. __________________ 1972 C/10 Cheyenne Super SWB. Restored, loaded, slammed. 1968 C/10 50th Anniversary LWB. Unrestored, stock, daily driver/work truck. RIP ElJay RIP 67ChevyRedneck RIP Grumpy Old Man

05-06-2019, 06:48 PM	#2
57taskforce All about them K’s Join Date: Jun 2014 Location: Farmington, New Mexico Posts: 6,282	Re: 700 r4 in a K20? There’s a few ways to skin this cat. The first is a shortened transmission output shaft that will then let you use the th350 adaptor to your 205. The second is a spacer that goes between the adaptor and the transmission that lets you keep the stock Kcase 700r4 output shaft. If your going to go thru the tranny use option 1. I looked into this a year or two back so this is just the gist of it. If I remember right you may have to move the motor forward because the 700r4 is longer than the th350. Don’t quote me on it though. I was in your neck of the woods last month in my Camaro. The freeway can be pretty fun with 400hp and a 6 speed. If I was in my K20 with no overdrive, not so much. It’s not that I worry about the engine speed or anything like that, I just don’t care to go 80-90 in that beast. __________________ Tyler '57 3100 http://67-72chevytrucks.com/vboard/s...d.php?t=813888 '72 K20 Cheyenne http://67-72chevytrucks.com/vboard/s...d.php?t=662879 ‘69 K10 SWB http://67-72chevytrucks.com/vboard/s...d.php?t=805206 '98 Silverado LT K2500HD ECLB Vortec 454/4l80E: 6" lift 315/75/16's ‘87 IROC-Z all original 50K mile survivor TPI 305 IROC Blue ‘10 Camaro 2SS/RS Aqua Blue Metallic #93 -version 2.0 Last edited by 57taskforce; 05-06-2019 at 08:11 PM.

05-06-2019, 08:07 PM	#3
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,862	Re: 700 r4 in a K20? Yes, you move engine forward so the transfer case stays in the same place so the driveshafts can go untouched. __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~

05-06-2019, 08:28 PM	#4
jocko Senior Member Join Date: Oct 2009 Location: Godley, TX Posts: 17,939	Re: 700 r4 in a K20? If trans is a 2WD unit, need the shortened output shaft HERE Original K-case is slightly stronger because of a 6-bolt torque converter cover, but unless you're going baja, probably not necessary. Torque converter cover bolt holes may be a clue - I think if 2WD, there may only be 4(?) K-case had 6 I believe. EDIT: I believe doing the output shaft swap and moving the engine fwd as Tim mentions is the preferred approach. Last edited by jocko; 05-06-2019 at 08:34 PM.

05-06-2019, 08:49 PM	#5
leddzepp Moderator Join Date: May 2007 Location: Southern Cal Posts: 19,994	Re: 700 r4 in a K20? Sorry, I should have specified the 700 is a 2wd transmission. Thanks for the input so far everyone! __________________ 1972 C/10 Cheyenne Super SWB. Restored, loaded, slammed. 1968 C/10 50th Anniversary LWB. Unrestored, stock, daily driver/work truck. RIP ElJay RIP 67ChevyRedneck RIP Grumpy Old Man

05-07-2019, 09:05 AM	#6
Mts67C10K20 Senior Member Join Date: May 2017 Location: Dowagiac Michigan Posts: 202	Re: 700 r4 in a K20? Did this last year All correct so far You need an output shaft installed for a 4x4 You can use a stock one with advanced adapters , adapter Or a modified shaft and a 350t adapter Then move motor forward 2" Also will need the presure cable and carb bracket and a lockup kit There are many out there Have fun Having overdrive is the only way to go imo

05-07-2019, 01:49 PM	#7
Bigdav160 Registered User Join Date: Apr 2011 Location: Klein Texas Posts: 3,852	Re: 700 r4 in a K20? I've done it too and used the AA output shaft. Things I learned: my factory 4x4 fan shroud no longer fit the coolant hoses had to be modified my A/C lines had to be modified I had to move the shift linkage forward on the frame I notched the front crossmember for crank pulley clearance The transmission pan is really close to the front driveshaft but clears possibly because I have a 2" lift The exhaust pipes had to be lengthened Otherwise I would do it again __________________ 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



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