I need help with what overdrive to install.

[dropanddrag71]

1970 c-20 3/4 ton automatic 2 wheel drive column shift, factory stock.....
I want to install an overdrive automatic in my stock truck. thing is i know nothing on whats what. I would like to install a direct fit, where i can just put it in drive on my column shift and go. I do not want any computers or sensors ect.. I want to go to a tranny shop and have this done but i also have zero knowledge on this area. Can you all educate me on what i want so when i go to the shop i will not get talked into something thats not what i want and i dont sound like a fool.

[SS Tim]

If you are going to tow with it, a Gear Vendors O/D unit is the best choice. Turns your three speed into a six speed. They can often be found used. Are you running a TH350 or TH400 now?

http://www.gearvendors.com/faq.html

[Scott>72-GMC]

I have seen these before. Do they basically bolt up to the existing tranny
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[70blackfish]

I had a gear vendors OD Hated it....nothing but problems. it was suppose to be good for 1200 hp..I put 750 hp to it...didnt last long and took out my trans too.....

go with a 700r4its a chevy trans used in a lot of trucks and cars..

[SS Tim]

I'd be interested in the back story, they have a very good operational record.

[TobyArnot]

Originally Posted by dropanddrag71

1970 c-20 3/4 ton automatic 2 wheel drive column shift, factory stock.....
I want to install an overdrive automatic in my stock truck. thing is i know nothing on whats what. I would like to install a direct fit, where i can just put it in drive on my column shift and go. I do not want any computers or sensors ect.. I want to go to a tranny shop and have this done but i also have zero knowledge on this area. Can you all educate me on what i want so when i go to the shop i will not get talked into something thats not what i want and i dont sound like a fool.

IF YOU HAVE A TH400, disregard this post ! A 200R4 is as close to a bolt-in as you're going to find for a TH350. Same length, no driveshaft mods. A good 200R4 will easily handle a stock V-8.

[MARKDTN]

I would go with a 700R4. That is what GM used behind anything with power. You can use a 200R4 and people point to how good they are, and that is correct. But what is not often pointed out is that a 200R4 requires upgrades and rebuilding to stand up to much abuse. The 200R4 was never used behind a 350, let alone a 454. The biggest stock application was the "mighty" 307 Olds. 700R4 got a bad rap early, but they are good if you follow a few guidelines 1) '89 and up have better internals. Find one of these. 2) you MUST adjust the TV cable before the vehicle moves even an inch. It is CRITICAL to have a working and properly adjusted TV cable. If you have a Qjet carb, use an aftermarket plate or one from a mid to late 80s pickup, van, or Caprice with 700R4. The mount is not a big deal. You will have to cut the driveshaft. With either the 200R4 or 700R4 you will have to hook up lockup. There are kits available from Bow Tie Overdrives, Howell, Painless, Street and Performance, etc.

[Tom Vogel]

Originally Posted by SS Tim

If you are going to tow with it, a Gear Vendors O/D unit is the best choice. Turns your three speed into a six speed. They can often be found used. Are you running a TH350 or TH400 now?

http://www.gearvendors.com/faq.html

^^^^ X2

[QUOTE=70blackfish;5857427]I had a gear vendors OD Hated it....nothing but problems. it was suppose to be good for 1200 hp..I put 750 hp to it...didnt last long and took out my trans too.....

QUOTE]

Well... thats one for the record books. Did you call Gear Vendors? What did they say? In all the years Ive been following these things, yours is the first. They put these things in huge trucks/motorhomes and race cars and they are the Schnitz! Yours is the first complaint.
MARKDTN... You would so love one of these.

[69GWC]

The gearvenders unit sounds like more of what your after. From what I have read about them its a pretty straight forward install and then have the drive shaft cut down.
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[Lemield]

I have a Gear Vendors overdrive in my CST. Simple to install and simple to operate. I really like it. Had to shorten the driveshaft so it was a good excuse to get rid of the carrier bearing too. I have had zero problems with mine.

[cdowns]

how do you plan on using your truck// what sixe tires and current rear end ratio?

overdrive is really only good if you plan to do a high percentage of your driving on the open highway

[Scott>72-GMC]

My uncle does alot of highway driving but in Colorado highway is 65 interstate 75 he can't hardly keep up in his 68 set up he wants to drop the truck on a 90s truck frame and drivetrain
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[MARKDTN]

Originally Posted by Scott>72-GMC

My uncle does alot of highway driving but in Colorado highway is 65 interstate 75 he can't hardly keep up in his 68 set up he wants to drop the truck on a 90s truck frame and drivetrain
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He is on the right track, but you don't have to go to that extreme. My '83 K20 had a 350 and 700R4 with 3.42 gears. On the highway-particularly with a load- you were always in the gas to maintain 65 mph. I swapped in a bone-stock L98 Corvette Tuned-Port and my mileage jumped from 14/17 to 18/21. And pulling a load is much easier. I can run 70+ all day long without revving. The late drivetrain swap is a good option.

[Scott>72-GMC]

I like that much better I would like to keep mine as stock as possible not swap frames but mines going to be a Sunday driver as well. I think my uncle has a smaller engine as well so I'm sure that makes a difference
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[eldogg]

Originally Posted by MARKDTN

I would go with a 700R4. That is what GM used behind anything with power. You can use a 200R4 and people point to how good they are, and that is correct. But what is not often pointed out is that a 200R4 requires upgrades and rebuilding to stand up to much abuse. The 200R4 was never used behind a 350, let alone a 454. The biggest stock application was the "mighty" 307 Olds. 700R4 got a bad rap early, but they are good if you follow a few guidelines 1) '89 and up have better internals. Find one of these. 2) you MUST adjust the TV cable before the vehicle moves even an inch. It is CRITICAL to have a working and properly adjusted TV cable. If you have a Qjet carb, use an aftermarket plate or one from a mid to late 80s pickup, van, or Caprice with 700R4. The mount is not a big deal. You will have to cut the driveshaft. With either the 200R4 or 700R4 you will have to hook up lockup. There are kits available from Bow Tie Overdrives, Howell, Painless, Street and Performance, etc.

200-4r was in Buick Grand Nationals and held up fairly well. I prefer the gear ratios in a 200 4r over a 700r4 but I would not install any transmission without it being rebuilt first. You have to remember the last non computer controlled trans was 1996 (16 years ago). If you have th400 I would just install a Gear Vendors overdrive.

[b.eddy's72]

Gear Vendors is a great route if you have $2800 to spend on one. I found a used one for $2200.

700's and 200's are a dime a dozen and most tranny shops should be able to complete the swap in a couple of days.

A different set of gears in the rear is an option too.

If the money was there I would do the Gear Vendors, but I am going to swap in a 700r4 and a different rear because at 55mph im doing 3000 rpms.

P.S. I also have never heard of any problems with the GV unit but they are mechanical and do wear out.

[cdowns]

saw this listed last night// i thought a bit high for a used unit but he might b reasonable


http://daytona.craigslist.org/search...inAsk=&maxAsk=

[turbosix]

Originally Posted by eldogg

200-4r was in Buick Grand Nationals and held up fairly well. I prefer the gear ratios in a 200 4r over a 700r4 but I would not install any transmission without it being rebuilt first. You have to remember the last non computer controlled trans was 1996 (16 years ago). If you have th400 I would just install a Gear Vendors overdrive.

I agree. I bought my GN with 65K easy miles on it. Put a tranny cooler in and made many a low 12 second pass and hard daily driving for another 35K miles and the tranny has held up great. I'm putting a 200 in my 68 one day. The Turbo buicks came with 3:42 gears and the Monte Carlo SS had 3:73 gears.

[b.eddy's72]

Originally Posted by cdowns

saw this listed last night// i thought a bit high for a used unit but he might b reasonable


http://daytona.craigslist.org/search...inAsk=&maxAsk=

if I had $1400 extra laying around he would be shipping to to Weatherford TX

[jocko]

I'm assuming you have a TH350, but that is a big assumption. Could be a TH400, so would help if you could confirm (unless I missed that above somewhere).

I have a 71 C20 with a TH350 and 4.10 rear end with 31.7" tall tires (265-75-16). If you have a different combo, let me know and I can post the same info for you for your application.

When the time comes, I plan to go with a Bowtie Overdrives 2004R - here's the comparison, and you can tell I had already decided... (but 700R4 included as a comparison).

Agree with the above posts, 200 would require some less mods than a 700 to install, and built up a bit, either will be more than sufficient behind your 350.

One note, depending on your use (heavy towing, for example??) might want to consider all options. Also, if you have an original TH400, I might then be more inclined to go with a GV o/u unit. They are nice, but also a good bit more expensive than an entire new trans. And keep in mind - if you install one, you still have an OLD trans in front of it.

Anyway, here are the #'s:

[Ziegelsteinfaust]

Have you considered a 4L80 or 4L85?

You can get them quite cheap. Around $150 core or $500 if it has a warranty. A controller cost $700, and Car Craft just did a story on them. Plus a rebuild now a days is under $1000 provided its a basic one. More if you have bad solenoids.

I am likely doing the T200R4 for my truck unless I go for the 4L80 because I found a deal.

[AustinScott]

Check out my build thread. I went from a Th400 to a bowties 2004r. I just swapped out my rear from 308 to 3.73 posi.

The 2004r and th400 mounting size is so close when I did my swap the trans cross member didn't have to move. Just got a new mount and I was set.

I have a few hundred miles on my new setup. I can't complain.. the truck loves the freeway and will hold its own stop light to stop light.

Few words of advice, brake pedal lock up release is good, but I also put in a toggle switch for the lockup, the 2004r seems to like to shift into 4 at low speed and then lock up... Not a good combo for your engine...

Feel free to hit me up for any thing related to the swap I'm happy to help any way I can.

Scott
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[JointTech]

can somebody explain fi the gear vendors overdrive is automatic or something you have to switch? Is it really like 6 gears without pushing a button? I cant find anywhere on the site that says for sure because in some places it says "you can choose..." which to me means theres some kind of toggle?

Do you have to drive it like my old split rear axle dump truck? 1l-1h-2l-2h-3l-3h

[JointTech]

Originally Posted by JointTech

I just can't imagine a car that can do all these things without a Gearvendor overdrive unit installed. Additionally, the electronic control unit allows me the flexibility to manually engage the overdrive unit or just let the computer do it for me!

Finally found that in a testimonial. Cool!!

[haysonj]

Originally Posted by JointTech

can somebody explain fi the gear vendors overdrive is automatic or something you have to switch? Is it really like 6 gears without pushing a button? I cant find anywhere on the site that says for sure because in some places it says "you can choose..." which to me means theres some kind of toggle?

Do you have to drive it like my old split rear axle dump truck? 1l-1h-2l-2h-3l-3h

The GV has a switch which can be switched from Auto to Manual In auto it switches like a automatic Mine will go from 1 to 2 to 2 over then 3 over in manual there is another switch ( either on the floor like a dimmer or like mine in the handle of the floor shift) wich you a can shift the unit in and out so you go from 1 to 1o to 2 to 2o to 3 to 3o hince the six speed. I use mine to tow a 5000 lb boat so I can always find the right gear to pull a hill.