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#1 |
Senior Member
Join Date: Jul 2001
Location: Ridgecrest, CA
Posts: 318
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search down....auto to manual tranny swap????
I have to change my old junky 3 speed for an automatic in my 71 half ton suburban..... here is what I think I know about the job.
1. I need a flywheel, starter, torque converter, shifter, and crossmember, is there anything else? 2. I am taking out a three on the tree tranny, I think I can put in a turbo 350 without changing the driveshaft..... 3. I just happen to have a parts truck with a rebuilt tranny.... but its a turbo 400! and a 3/4 ton, while my burb is a 1/2 ton. Question.... if I use the 400, can I use the driveshaft from the parts truck? It is a 69 longbed. Or would it be easier to try to get a turbo 350? Then I wouldn't have to do all the work of removing the other tranny from the parts truck, but I would have to get all the parts. Need IIIIIINNNNNPPPPUUUUTTTT!!!!! I know this has been talked about on here many times, but search is not working so I have to ask. Anyone? Anyone? Bueller??? p.s. here is a picture of my burb overlooking Panamint Valley, this is aout 45 minutes from my house... ![]()
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57 suburban(sitting in the driveway), 2 69 C20 longbeds (sitting in the field ) and a 2003 8.1 Suburban ![]() Endeavor to persevere. "All of a sudden, I'm the old timer!" Some old timer on American Pickers. |
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#2 |
Registered User
Join Date: Jan 2002
Location: Springville, UT, USA
Posts: 1,010
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You have to do a bunch of things......first you have to change the gearing of your rear end......then you have to change the hump in your sled......then you'll have to get a new driveline made for whatever tranny you decide on considering there are several lengths in the TH350 and 400's......you'll need a cradle as well.....big job man......I'd take what you got and swap with another one with a tranny already here.....broken or not it's easier to replace......but do more research and consult with a tranny shop on this as to you don't want to jump into a project swap like this with info from this board.....don't get me wrong....this board is great but ideas are one thing......but directions on what to do for what you are planning need to be done with the aid of a onsite pro.
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#3 |
Account Suspended
Join Date: Sep 2000
Posts: 4,002
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Why would the starter have to be changed?
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#4 |
Fabricate till you "puke"
Join Date: Jun 2002
Location: Ill
Posts: 9,403
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your 3spdstick+bell, is the same lenght & yolk spline as a 350 turbo with a 6" tailshaft. The short 400 turbo (4" tail) is approx 11/16" longer, & has a different slip yolk(no biggie), as you can have the shaft shortened pretty cheap. you will need to remove the bellmount crossmember, & install an auto crossmember under the trans. Other than that, pretty much all you have listed, plus a cooler & lines & the auto shifter. You can replace the column, or just add a B&M floor shifter, which i feel would be much easier. The 400 turbo is a d@mn good trans, & personally if you have a rebuilt unit, I would run it
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69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears.... |
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#5 |
Account Suspended
Join Date: Sep 2000
Posts: 4,002
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I have a 250 6cyl with a 3spd that I want to make auto, Is there any point going with an overdrive tranny or should I stick with a th350. The truck will just be a daily driver, will the OD get me some extra mileage?
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#6 |
Registered User
Join Date: Mar 2003
Location: Stillwater MN
Posts: 1,166
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The OD trans will help mpg on the highway.
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69 GMC K10 ..some restoration required....still.. ![]() |
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#7 |
Fabricate till you "puke"
Join Date: Jun 2002
Location: Ill
Posts: 9,403
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Gee_Emm,I havent tryed an O/D behind a I6, but my bet would be with the 3.73 gears in a 1/2 ton 6 /stick, you could probably pick up a little milage on the hyway. If you are primarily a town driver, I dont know that I would spend the extra cash for the 700 r4. 350 turbos are cheap, & pretty reliable. Good luck,crazyL
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69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears.... |
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#8 |
Senior Member
![]() Join Date: Mar 2001
Location: Cedar Park, TX
Posts: 686
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You dont need to modify the "hump" in the cab with a TH350 or
a 700R4. I have a small hump and they both fit fine. MIght need to modify with the TH400, not sure on that one. Get ALL the shifer linkage possible, including that "C-CLIP" piece bolted to the tranny shifter selector...been discountinued from GM. Its not hard to do, but getting the standard transmission crossbrace out isnt fun, you'll also need an automatic cross-member and mount (with shim). My speedo-cable was really short and barely made it. It was quite a bit of work, but well worth it, as my shift linkage would bind up in third ALL the time.
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71 Chevy C-10 SWB Fleetside RamJet-350/4L60e & Compushift/3.73Posi See it at www.prismnet.com/~grzanich |
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#9 |
Account Suspended
Join Date: Sep 2000
Posts: 4,002
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The 400 will fit under a small hump
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#10 |
Registered User
Join Date: Mar 2003
Location: Stillwater MN
Posts: 1,166
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I was led to believe all the standard trans trucks came with the high hump installed.
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69 GMC K10 ..some restoration required....still.. ![]() |
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#11 |
Account Suspended
Join Date: Sep 2000
Posts: 4,002
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Nope both of mine are low hump
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#12 |
Fabricate till you "puke"
Join Date: Jun 2002
Location: Ill
Posts: 9,403
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The 2wd 4 spd trucks were a high hump(ch465), as were the 4wd trucks. Any of the auto trans equipped 2wd trucks(I 6 or sb ), or 3 spd stick were low hump. I think from some of the posts ,I heard that the BB 2 wd trucks were a high hump with the auto trans.....I havent been into the BB trucks, so somebody that has been there will have to comment on that . crazyL
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69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears.... |
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