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#1 |
Registered User
Join Date: May 2012
Location: Anchorage, Alaska
Posts: 7
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1971 Drivetrain options
Hi guys,
I'm sure this has been asked before, but I didn't find an answer. I have a 1971 3/4 4x4 with no drivetrain. I'm wondering what year rigs I can start looking for to find a drop in donor motor/trans/case. Haven't seen too many '71/72's around for donors. Thanks for the assistance!! |
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#2 |
the boat guy
Join Date: Jul 2007
Location: springfield mo
Posts: 2,339
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Re: 1971 Drivetrain options
1955-2016 gm will all drop in with some small adapters and redrilling a few holes.
__________________
67, swb, fleet, tach, throttle, 5.3, 4l60e, 3.73's, fuel cell, 5 lug, p.d.b., 4-6 drop. great little truck 66, stevens drag/ski 18' silouette, 350, 2.02 doublehump heads. comp extreme marine 278 cam, vette 7 fin valve covers, old polished edelbrock intake, velvetdrive, casale v-drive, adj cavitation plate. 28, model a rpu project, |
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#3 |
Registered User
Join Date: Jan 2015
Location: Clyde KS
Posts: 91
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Re: 1971 Drivetrain options
The factory didn't build any big block 4x4's so if you want to go original you'll have to stick to a small block chevy. Big block chevy motors will fit but it'll be a tight fit. Stock transmission options were the 4 speed or th350.
Ugly 61 |
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#4 |
Registered User
Join Date: Oct 2015
Location: Waskatenau, Alberta
Posts: 259
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Re: 1971 Drivetrain options
You didn't mention if your 71 was originally a standard or auto? Chances are your truck came with a 307 or a 350. If I was doing the job, would try find a mid to late 70's doner truck with everything you need. I believe around 1980 was the last year they used the NP205 transfer case.
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#5 |
Registered User
Join Date: May 2012
Location: Anchorage, Alaska
Posts: 7
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Re: 1971 Drivetrain options
Thanks guys,
Any combo drops in as long as it's a 4x4 case? |
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#6 |
Registered User
Join Date: May 2012
Location: Anchorage, Alaska
Posts: 7
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Re: 1971 Drivetrain options
Thanks Barry, not sure (I can check the VIN) what it originally came with. I did get a T350/205 with it when purchased.
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#7 |
Vintage 4x4s
Join Date: Sep 2010
Location: Prior Lake, MN
Posts: 4,305
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Re: 1971 Drivetrain options
Are you missing the tcase too? If so, I'd look for a 1970 to 1987 GM 4x4 setup. Just make sure you get a right hand drop tcase setup. On that note, 1989 to 1993 dodge cummins will fit and work well but requires new crossmembers and is a bit more involved project.
__________________
67 GMC K1500 Custom- 305V6 SM420, PTO, Ram Assist, yellow (the outcast) (project period correct upgrades) 67 GMC C2500 351V6 TH400, AC, PS, PB (can't decide what to do with. Update, decided to keep and will restore ![]() 86 CHV K30 502 th400, apple red NEW 71 CHV K20 350 SM465, ochre (saved work truck) 71 CHV K20 292 SM465, white, tach, PTO, (future project) 72 CHV K20 350 350th, medium blue (project stocker) 01 CHV K2500hd crew, indigo blue ^3 dont run and the others don't see winter either '86 K30 Cummins "Fireside" thread: http://67-72chevytrucks.com/vboard/s...d.php?t=649649 '71 K20 "get driveable" thread: http://67-72chevytrucks.com/vboard/s...d.php?t=590642 '72 K20 Build Thread: http://67-72chevytrucks.com/vboard/s...=493477&page=6 |
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#8 |
Vintage 4x4s
Join Date: Sep 2010
Location: Prior Lake, MN
Posts: 4,305
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Re: 1971 Drivetrain options
I was typing as you were. If you have the np205 with auto trans adapters you are in good shape and just need pretty much any SBC. You may want to consider a 700R4 upgrade since it will work with your np205
__________________
67 GMC K1500 Custom- 305V6 SM420, PTO, Ram Assist, yellow (the outcast) (project period correct upgrades) 67 GMC C2500 351V6 TH400, AC, PS, PB (can't decide what to do with. Update, decided to keep and will restore ![]() 86 CHV K30 502 th400, apple red NEW 71 CHV K20 350 SM465, ochre (saved work truck) 71 CHV K20 292 SM465, white, tach, PTO, (future project) 72 CHV K20 350 350th, medium blue (project stocker) 01 CHV K2500hd crew, indigo blue ^3 dont run and the others don't see winter either '86 K30 Cummins "Fireside" thread: http://67-72chevytrucks.com/vboard/s...d.php?t=649649 '71 K20 "get driveable" thread: http://67-72chevytrucks.com/vboard/s...d.php?t=590642 '72 K20 Build Thread: http://67-72chevytrucks.com/vboard/s...=493477&page=6 |
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#9 |
Registered User
Join Date: May 2012
Location: Anchorage, Alaska
Posts: 7
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Re: 1971 Drivetrain options
Thanks Vintage,
To Brad's point, anything including the 700R4 will bolt in? |
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#10 |
Special Order
![]() ![]() Join Date: Nov 2004
Location: Mt Airy, MD
Posts: 85,859
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Re: 1971 Drivetrain options
The 700r4 is longer than the TH350, so the crossmember for the transfer case will need to be moved back. But first, do you have the driveshafts? If no, then that is a good way to go since the stock front would need to be lengthened and the rear shortened and you'd be having them made anyway. If you do have the driveshafts you can do the 700r4 conversion w/o touching the shafts. You just move everything forward the difference in length and they'll work. Inline 6s in these trucks have mounts further forward and the holes will be in the frame, so just move yours there. 4wd engines sit way back anyway and there is plenty of room in front. Also, the distributor will be easier to work on.
__________________
"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 ~ |
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#11 |
Registered User
Join Date: May 2012
Location: Anchorage, Alaska
Posts: 7
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Re: 1971 Drivetrain options
Yep, got the factory driveshafts.
If I find a donor in my vintage, is there any difference in the frame on a 1/2 ton vs. 3/4 ton when considering swapping over the drive-train? Thanks guys. |
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#12 |
Registered User
Join Date: May 2012
Location: Anchorage, Alaska
Posts: 7
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Re: 1971 Drivetrain options
Vintage,
I do have an opportunity to pick up a 350/SM465/NP205 from a '78 donor. I noticed you have that set up in your '71 K20. Was that a simple swap? Thank you. |
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#13 |
Registered User
Join Date: Oct 2015
Location: Waskatenau, Alberta
Posts: 259
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Re: 1971 Drivetrain options
Hi again Ryan, does your truck have a clutch pedal? If so, the 78 donor will work just fine. Installing a clutch pedal is not a nice job. You will need a 67-72 standard donor for the pedal setup.
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#14 | |
Vintage 4x4s
Join Date: Sep 2010
Location: Prior Lake, MN
Posts: 4,305
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Re: 1971 Drivetrain options
Quote:
In that same truck of mine, I swapped in a 350 that seemed to run well from another K20. I am regretting it now since it has developed a valve issue already. I've got a new crate engine I picked up for 1500 delivered sitting here ready to go in. Should have just bought the crate engine in the first place or rebuilt the 350. I am pretty sure I'm going to replace the TH350 in my 72K20 with a 700R4. I would really like the lockup converter and to have the engine further forward for servicing as special K mentions. I even have a OD shift indicator for my steering column.
__________________
67 GMC K1500 Custom- 305V6 SM420, PTO, Ram Assist, yellow (the outcast) (project period correct upgrades) 67 GMC C2500 351V6 TH400, AC, PS, PB (can't decide what to do with. Update, decided to keep and will restore ![]() 86 CHV K30 502 th400, apple red NEW 71 CHV K20 350 SM465, ochre (saved work truck) 71 CHV K20 292 SM465, white, tach, PTO, (future project) 72 CHV K20 350 350th, medium blue (project stocker) 01 CHV K2500hd crew, indigo blue ^3 dont run and the others don't see winter either '86 K30 Cummins "Fireside" thread: http://67-72chevytrucks.com/vboard/s...d.php?t=649649 '71 K20 "get driveable" thread: http://67-72chevytrucks.com/vboard/s...d.php?t=590642 '72 K20 Build Thread: http://67-72chevytrucks.com/vboard/s...=493477&page=6 |
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#15 |
Registered User
Join Date: May 2012
Location: Anchorage, Alaska
Posts: 7
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Re: 1971 Drivetrain options
Thanks Barry/Vintage,
I'll dig out the snow and confirm what I'm working with before landing on a donor. More to come... |
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#16 |
Special Order
![]() ![]() Join Date: Nov 2004
Location: Mt Airy, MD
Posts: 85,859
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Re: 1971 Drivetrain options
No difference between K/10 and K/20 frames when it comes to mounting drivetrain. Totally interchangeable.
__________________
"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 ~ |
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