72 Chevy 4x4 (converting 4 speed to automatic) - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**72 Super** · 11-05-2008, 08:06 PM

What all is involved in converting a 71-72 Chevy 1/2 4x4 ton from a factory 4 speed to a automatic. I mainly need to know is the transfer case and drive shafts the same? Other than the trans and related items what else would be needed? I know the column and pedal set up would be changed.

Thanks,Ray

drbyrdman · 11-05-2008, 08:36 PM

Iam doing one right now. Just take the clutch rod out and patch the hole in the fire wall,remove the clutch pedal and plastic bushings, get a auto floor shifter of some kind (B&M has a truck mega shifter that works good and does not cost alot), your going to have to move the transfer case mount and lengthen or shorten the drive shafts depending on what tranny you use. I would do some searching around and find a 350/205 or 400/205 combo for sale or do what I did and get a turbo 400 tranny and a tranny adapter to put a 350 or 400 tranny to the 205 transfer case.

**kwmech** · 11-05-2008, 11:12 PM

If you go with the turbo 350 the overall length will be the same

**72 Super** · 11-06-2008, 09:01 PM

Kwmech, I was planning on going with as turbo 350 trans/ with a 205 transfer case. So the drive shafts will be the same?

Drbyrdman, was you truck a factory 4x4? This seems like alot of changing for me. I was hoping that all was needed to be done was changing the trans and transfer case.

Thanks,Ray

**72 Super** · 11-06-2008, 10:01 PM

I posted this in the 4x4 section as well,just trying to get alittle more info. I am looking at 72 4x4 that is a factory 4 speed. Are the driveshafts the same length from a 4 speed versus automatic truck? Would the tranfer case be in the same location? I am just trying to figure what all is involved in switching over a manual to automatic.

Thanks,
Ray

**special-K** · 11-06-2008, 11:06 PM

It`s as simple as swapping the t-case/tranny combos and deleting uneeded manual pieces like clutch pedal & linkage and adding Automatic shifter.

knsmodels · 11-07-2008, 12:05 AM

Pretty sure you need the the transfer case, tranny, and driveshaft from an automatic for the conversion......transfer case shifter should remain in the same location and 4-speed.......

drivethechevy · 11-07-2008, 12:31 AM

when i first picked up my 68k10 4speed a few months ago i was thinking of doing a swap to an auto, i determined that the best route was getting a tranny and tcase from a newer truck, and i was going to have a driveshaft built if needed, the driveshafts, the tranny xmember and the linkage's seemed to be the bigger problems
but nothing some drilling a floor shifter and custom drive shafts wouldnt fix
hope that helped you some
good luck

JimKshortstep4x4 · 11-07-2008, 06:40 AM

The drive shafts are the same length so you can reuse them. Outside of the tranny and auto transfer case you will need the shift linkage and steering column. It is a pretty straight forward swap out.

My 71 snow plow had the manual (3) on the tree transmission that I swapped out and it sure is easier to plow with an automatic!

Jim

Mudder · 11-07-2008, 08:38 AM

flex plate for the auto and you will be lucky if you don't have to alter driveshaft lengths. Oh tranny lines for the cooler.

when i did my daughters, I left the clutch petal and after disconnecting it stuck it under the carpet so that it would still be there if we ever wanted to go back to the 4 speed, which the son in law did.

**CUSTOM/10** · 11-07-2008, 09:24 AM

I've done the same swap :

If the truck currently has an NP205 ( standard ) and your installing an NP205 ( auto & TH350 ) the drive shafts will remain the same, the cross member will remain the same & stay in the same location.

Other things you'll need:

auto steering coulomb
auto linkage & frame bracket
trany cooler & lines
kick down cable & brackets
flywheel
starter
flywheel cover
remove clutch peddle assem or you can install an auto brack peddle assem
patch floor hump or get a new one for an auto
The nutral safety switch is needed on the coulomb instead of on the trany

That's everything I can think of at the moment.

Gary

**71blksuper4x4** · 11-07-2008, 09:26 AM

That, and you might want to pick up a automatic 4x4 floor hump. Otherwise you will need to block off the stickshift hole.

BLACK AND BLUE 67-72 · 11-07-2008, 09:55 AM

No the driveshafts are different, the rear shaft will have to be shortened. The 4speed trans is shorter than the 3speed.

**CPNE** · 11-07-2008, 11:37 AM

I believe JimK is correct. If you are talking about a swap from a 4speed/NP205 to a TH350/NP205, the driveshaft lengths are the same and the xfer case bolts in the same position on the frame. The difference in overall length between the two trannys is offset by the adaptor that mates the tranny to the transfercase.

**72 Super** · 11-07-2008, 08:50 PM

Thanks for the replies. I would be going with turbo350/205 set up.I moreless had everything else in mind, I was mainly worried about the transfer case position and the lengths of the driveshafts.

Thanks,
Ray

sweet70beast · 11-11-2008, 01:07 AM

Make sure you remove the pilot bearing from the back of the crankshaft or when you put in the auto the snoute on the torque converter fits inside the part on the same spot and will push on it and could shorten the life of your thrust bearing in your engine. Not to mention it might bend or crack the flexplate.

11-05-2008, 08:06 PM	#1
72 Super Senior Member Join Date: Jul 2001 Location: Hyattsville, Maryland Posts: 3,685	72 Chevy 4x4 (converting 4 speed to automatic) What all is involved in converting a 71-72 Chevy 1/2 4x4 ton from a factory 4 speed to a automatic. I mainly need to know is the transfer case and drive shafts the same? Other than the trans and related items what else would be needed? I know the column and pedal set up would be changed. Thanks,Ray __________________ 72 Cheyenne Super (Purchased new by my parents in August of 71) Black and White Last edited by 72 Super; 11-05-2008 at 08:07 PM.

11-05-2008, 08:36 PM	#2
drbyrdman Registered User Join Date: Feb 2006 Location: San Diego Posts: 631	Re: 72 Chevy 4x4 (converting 4 speed to automatic) Iam doing one right now. Just take the clutch rod out and patch the hole in the fire wall,remove the clutch pedal and plastic bushings, get a auto floor shifter of some kind (B&M has a truck mega shifter that works good and does not cost alot), your going to have to move the transfer case mount and lengthen or shorten the drive shafts depending on what tranny you use. I would do some searching around and find a 350/205 or 400/205 combo for sale or do what I did and get a turbo 400 tranny and a tranny adapter to put a 350 or 400 tranny to the 205 transfer case.

11-05-2008, 11:12 PM	#3
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,630	Re: 72 Chevy 4x4 (converting 4 speed to automatic) If you go with the turbo 350 the overall length will be the same

11-06-2008, 09:01 PM	#4
72 Super Senior Member Join Date: Jul 2001 Location: Hyattsville, Maryland Posts: 3,685	Re: 72 Chevy 4x4 (converting 4 speed to automatic) Kwmech, I was planning on going with as turbo 350 trans/ with a 205 transfer case. So the drive shafts will be the same? Drbyrdman, was you truck a factory 4x4? This seems like alot of changing for me. I was hoping that all was needed to be done was changing the trans and transfer case. Thanks,Ray __________________ 72 Cheyenne Super (Purchased new by my parents in August of 71) Black and White

11-06-2008, 10:01 PM	#5
72 Super Senior Member Join Date: Jul 2001 Location: Hyattsville, Maryland Posts: 3,685	72 4x4 converting a factory 4 speed to an automatic I posted this in the 4x4 section as well,just trying to get alittle more info. I am looking at 72 4x4 that is a factory 4 speed. Are the driveshafts the same length from a 4 speed versus automatic truck? Would the tranfer case be in the same location? I am just trying to figure what all is involved in switching over a manual to automatic. Thanks, Ray __________________ 72 Cheyenne Super (Purchased new by my parents in August of 71) Black and White Last edited by 72 Super; 11-06-2008 at 10:02 PM.

11-06-2008, 11:06 PM	#6
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,851	Re: 72 Chevy 4x4 (converting 4 speed to automatic) It`s as simple as swapping the t-case/tranny combos and deleting uneeded manual pieces like clutch pedal & linkage and adding Automatic shifter. __________________ "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 ~

11-07-2008, 12:05 AM	#7
knsmodels I make Models Join Date: May 2005 Location: Bucks, PA Posts: 626	Re: 72 4x4 converting a factory 4 speed to an automatic Pretty sure you need the the transfer case, tranny, and driveshaft from an automatic for the conversion......transfer case shifter should remain in the same location and 4-speed....... __________________ Click to see what I do 1972 LWB K10 350/4 sp 1968 SS Chevelle 396/tremac5spd

11-07-2008, 12:31 AM	#8
drivethechevy Registered User Join Date: May 2007 Location: Buffalo MN Posts: 606	Re: 72 4x4 converting a factory 4 speed to an automatic when i first picked up my 68k10 4speed a few months ago i was thinking of doing a swap to an auto, i determined that the best route was getting a tranny and tcase from a newer truck, and i was going to have a driveshaft built if needed, the driveshafts, the tranny xmember and the linkage's seemed to be the bigger problems but nothing some drilling a floor shifter and custom drive shafts wouldnt fix hope that helped you some good luck __________________ Trial and Error, its expensive but its a mistake i most likely wont make again 1971 chevy k10 custom deluxe http://67-72chevytrucks.com/vboard/s...d.php?t=341257 1968 chevy k/10 fleet http://67-72chevytrucks.com/vboard/s...d.php?t=334731 1948 desoto custom coupe fluid drive(family heirloom)

11-07-2008, 06:40 AM	#9
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Re: 72 4x4 converting a factory 4 speed to an automatic The drive shafts are the same length so you can reuse them. Outside of the tranny and auto transfer case you will need the shift linkage and steering column. It is a pretty straight forward swap out. My 71 snow plow had the manual (3) on the tree transmission that I swapped out and it sure is easier to plow with an automatic! Jim __________________ 1971 Shortbox step side 4x4, 350 sbc, 3:07 rear end 1965 Impala SS 400 sbc, Muncie rock crusher 1966 Impala SS 396 bbc, TH 400 1969 El Camino, 350 sbc, TH 350 1971 Snowplow built on a Blazer frame 1972 GMC Short bed, stepside, TH 400, 427 BBC

11-07-2008, 08:38 AM	#10
Mudder Registered User Join Date: Feb 2001 Location: East Central, MO Posts: 11,336	Re: 72 Chevy 4x4 (converting 4 speed to automatic) flex plate for the auto and you will be lucky if you don't have to alter driveshaft lengths. Oh tranny lines for the cooler. when i did my daughters, I left the clutch petal and after disconnecting it stuck it under the carpet so that it would still be there if we ever wanted to go back to the 4 speed, which the son in law did. Last edited by Mudder; 11-07-2008 at 08:40 AM.

11-07-2008, 09:24 AM	#11
CUSTOM/10 Senior Member Join Date: May 2003 Location: Sandown, NH Posts: 2,850	Re: 72 Chevy 4x4 (converting 4 speed to automatic) I've done the same swap : If the truck currently has an NP205 ( standard ) and your installing an NP205 ( auto & TH350 ) the drive shafts will remain the same, the cross member will remain the same & stay in the same location. Other things you'll need: auto steering coulomb auto linkage & frame bracket trany cooler & lines kick down cable & brackets flywheel starter flywheel cover remove clutch peddle assem or you can install an auto brack peddle assem patch floor hump or get a new one for an auto The nutral safety switch is needed on the coulomb instead of on the trany That's everything I can think of at the moment. Gary __________________ Gary 72 SWB 4x4 My 72 SWB Build http://67-72chevytrucks.com/vboard/s...d.php?t=259859

11-07-2008, 09:26 AM	#12
71blksuper4x4 SWB 4x4 Collector Join Date: Jun 2001 Location: Osage City, KS Posts: 5,156	Re: 72 4x4 converting a factory 4 speed to an automatic That, and you might want to pick up a automatic 4x4 floor hump. Otherwise you will need to block off the stickshift hole. __________________ TREVOR 1970 CST swb 4x4 (speedwarning,cruise,tilt,tach,8track, original red shoulder belts,tow hooks) 1972 Jimmy (soon to be Hickey cloned) 1971 Cheyenne Super 4x4 swb (tilt,tach,buckets, original blue shoulder belts,am/fm,cruise,tow hooks, dealer 8 track) 1972 Cheyenne Super K20 4x4 Custom Camper (tilt, tach, am/fm, tow hooks, bed toolbox, aux gas tank 1972 Cheyenne Super Crew Cab K30 4x4 Duramax, Allison, np205, buckets, tow hooks (CURRENT PROJECT) http://67-72chevytrucks.com/vboard/s...d.php?t=624819 1989 V3500 Crew Cab (454tbi, NV4500, np205) 1970 Chevelle SS (LS5 454,th400,8track,buckets,tach) :2004 Jeep Wrangler Rubicon (daily driver) WTB: 1968-70 Cruise Control Lever

11-07-2008, 09:55 AM	#13
BLACK AND BLUE 67-72 Firefighter Join Date: Feb 2001 Location: Yellville, Ar, USA Posts: 1,943	Re: 72 4x4 converting a factory 4 speed to an automatic No the driveshafts are different, the rear shaft will have to be shortened. The 4speed trans is shorter than the 3speed. __________________ '72 Chevy SWB 350 Auto '67 GMC LWB 350 4 speed '70 Chevy 4x4 Stepside 350 Auto Yellville, Ar. USA

11-07-2008, 11:37 AM	#14
CPNE Resident Curmudgeon Join Date: Dec 1999 Location: NH Posts: 6,662	Re: 72 4x4 converting a factory 4 speed to an automatic I believe JimK is correct. If you are talking about a swap from a 4speed/NP205 to a TH350/NP205, the driveshaft lengths are the same and the xfer case bolts in the same position on the frame. The difference in overall length between the two trannys is offset by the adaptor that mates the tranny to the transfercase. __________________ Currently on or near the homestead: 67 Chevy SWB 2WD stepside 350/3 on tree (Pat's) 67 GMC SWB 2WD Fleet 402/auto (Brian's under construction) 67 Chevy 3/4 ton 2WD 402/auto (Business Hauler) 67 Chevy 1 ton dually 2WD 396/4 speed (Former business hauler, Needs TLC) 68 Chevy 1/2 ton Suburban 2WD 250 six/3 on tree (Brian's Needs TLC) 70 Chevy 3/4 ton 4WD 350/4 speed (Pat's - Disguised as a 68 GMC) 71 Chevy SWB stepside (Crushed by tree - parts donor) 72 Chevy 3/4 ton 4WD (Parts donor) 72 Chevy 3/4 ton 4WD Suburban (Parts Donor) 72 GMC 3/4 ton 4WD 292 six/4 speed (Mine - Disguised as a 67 GMC) 81 GMC 4WD Dually Dump Body 350/4 speed (Business Hauler) 82 Camaro Z/28 355/Super T-10 (Pat's toy) 93 Caprice 9C1 (Brian's Cop Car) 02 Toyota Camry (Reliable but a souless steel and plastic hulk) 2011 2SS RS Camaro M6 Factory Hurst Shifter Maybe I need to sell some of this crap Yet another Bozo with a sawz-all

11-07-2008, 08:50 PM	#15
72 Super Senior Member Join Date: Jul 2001 Location: Hyattsville, Maryland Posts: 3,685	Re: 72 Chevy 4x4 (converting 4 speed to automatic) Thanks for the replies. I would be going with turbo350/205 set up.I moreless had everything else in mind, I was mainly worried about the transfer case position and the lengths of the driveshafts. Thanks, Ray __________________ 72 Cheyenne Super (Purchased new by my parents in August of 71) Black and White



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11-11-2008, 01:07 AM	#16
sweet70beast Registered User Join Date: Sep 2006 Location: Shelley Idaho Posts: 876	Re: 72 Chevy 4x4 (converting 4 speed to automatic) Make sure you remove the pilot bearing from the back of the crankshaft or when you put in the auto the snoute on the torque converter fits inside the part on the same spot and will push on it and could shorten the life of your thrust bearing in your engine. Not to mention it might bend or crack the flexplate. __________________ 1970 Nova 327/T5 (my 1st car) 1971 K-20 350/350/205 (winter DD) 1953 GMC Suburban 1968 Chevy Bel Air 1976 Chev C-10 1972 Skylark (suncoupe) 1 of 3943 made Last edited by sweet70beast; 11-11-2008 at 01:09 AM.

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