In case you're thinking about a 4L80E...

[davepl]

I backed myself into a corner by choosing gears (4.88s) that require overdrive, since I was going to use a 200-4R I had on hand. Had that rebuilt and it lasted 48 miles (but 3 years, so no warranty).

So I decided on a 4L80E, basically the original TH400 but with overdrive.

Of course you need a computer to run that.

$650 KA-Ching.

But the computer doesn't work without a throttle position sensor.

$250 Ka-Ching.

And your speedo doesn't work without a speedometer control unit.

$500 KA-Ching.

And so it goes. That TH400 is looking pretty good right about now! I sure hope this thing works and drives well. The good news is that the TH400 is not my favorite shifting trans anyway, so maybe the 4L80E with the electronic control and accurate TPS (not a kickdown switch) will be nicer. Hope so!

But I'll be into it for about $2250 on the trans, $1200 for computer stuff, and probably a couple of thousand to install it, since I don't have a trans jack and these are too heavy to bounce around on a floor jack (I've bench-pressed powerglides into place, but these are heavy!).

- Dave

[Andy4639]

If you want to play you got to pay!

[67ChevyRedneck]

You don't have to explain to us

Just recently I just wanted to do a gear swap in my 65 Mustang (still in middle of it.)

3.25 trac loc 3rd member $960
Springs are SHOT, so Eaton GT springs $350
I want dual exhaust now, but on mustangs they were stupid and put the brake hose in the way, so dual exhaust cars got different brake stuff... $70 to relocate brake line properly.
$200 for parts to rebuild axles (bearing, seals) new stuff for springs, etc.
Probably $400 for exhaust when done.

But it was just a simple gear swap

Don't get me started on dropping my truck. The ECE kit was expensive enough, but I ended up with a fully rebuilt front suspension complete with new upper and lower control arms.

[trac209]

Sometimes the money you save in gas instead worth it if it's 3000k plus to put an od trans in. I want an od so I can cruise the highway without pissing off people behind me trying to pass my slow ass lol,and not to meantion the poor gas mileage and noise running at 2800-3000 rpm

[davepl]

Yeah, it sure wasn't about mileage, it was about having good torque (gearing) down low and still having a reasonable engine speed on the highway. Of course the original owner drove it 150,000 highway miles with 3.54s, but I had to change things...

Oh well, if it all works out, it'll be a nice setup!

[Andy4639]

I'm well into the 5000-10,000 for stuff. Motors transmissions and the such.

[BrianG]

You could always get another 200-4r redone. They are supposed to be good if they are done right.

[cleszkie]

With the money you spent plus money you are still planning on spending to finish the tranny work, could have just got yourself a Gear Vendors overdrive to bolt to the back of the 400TH in your own garage.

[kwmech]

Originally Posted by davepl

But I'll be into it for about $2250 on the trans, $1200 for computer stuff, and probably a couple of thousand to install it, since I don't have a trans jack and these are too heavy to bounce around on a floor jack (I've bench-pressed powerglides into place, but these are heavy!).

- Dave

At that point, money spent on a Gear Vendor you'd be ahead of the game

[PeterHall]

Cant you use a newer tach, cut it up, and swap it for like $80 plus your time?

[72MARIO]

We put a 4L80 in my dads 1973 with a 454 C20 to replace the T400. He loves it ability to adjust shift points and lock up converter with ease Its worth every penny. We used the TCI controller.

[kbill45@gmail.com]

A good trany man can beef up a 700R4 to close to 4L80 strength. No computer

[72MARIO]

Not sure why this big hype against computers.....Complete control of all the transmissions shift charactistcs. OE has been using computers to control engine and transmission reliably for years . 700R is a light duty transmission and has no place behind a big block in a 3/4 ton truck no matter who builds it.

[57taskforce]

Yea, a good tranny man could also do nothing at all except for maybe a stock rebuild, to a 4l80E and have it last hundreds of thousands of miles behind a big block. All while turning big tires or pulling heavy trailers daily, with little to nothing done to it over its service life other than regular maintenance. They are not equal even when one is built. The 80 and 85e are stout factory units. The 700r I have little good to say about given my personal experience with two of them in my vehicles. I've got two factory big block trucks with an 80e and an 85e. One behind a 7.4 with 35" tires and another behind an 8.1. Both over 200000, both all original save the fluid and filters. It may cost more to get the 80 transplanted but it will out live any 700r if taken care of. Not trying to be a jerk by any means at all I just believe they are in separate leagues built nor not.

[special-K]

I had the 4L80E/ECM out of my '91 diesel V2500 Suburban to put in my '72. I decided I am fine with driving a sensible speed just as I have since these trucks were new. I got rid of the trans. I don't let hyped out impatient people influence my actions. They need to learn patience, I don't have to let them push me. They are the one with the problem they need to deal with...or leave earlier so you don't end up behind me. The world needs to take a deep breath and slow down. I'm doing my part to affect that

[mike16]

oh and if your tranny's black box mallfunctions , it will cause the tranny to slip, malfunction and burn up too. You could be alternatly replacing box's and tranny's while you develope troubleshooting skills.

[Robznob11]

I like the gear vendors idea, but even better than that just sell your engine and get a lighter, more efficient bad a$$ ls motors and use stock computer! You will be way ahead of the game. These ls engine's can and do hang with big blocks every day😜

[1972RedNeck]

Originally Posted by Robznob11

I like the gear vendors idea, but even better than that just sell your engine and get a lighter, more efficient bad a$$ ls motors and use stock computer! You will be way ahead of the game. These ls engine's can and do hang with big blocks every day��

Have you seen the OP's truck? It is restored to almost perfect originality. There is no way that I would ever want to see anything but the original 402 under the hood. I don't think the OP would either...

[special-K]

Original big blocks belong in original big block vehicles. Many people have lost sight of how great these trucks came from factory and only see them as another place to stuff their LS. I may end up with an LS in one of these trucks, if I was going to daily drive it, but I will always think first, then decide when and if it's a good idea. The small block Chevy engine was by many counts, one of the greatest engines ever made. You can't really compare them to what came later. But what came later is what it is because it had the SBC of proven 55 or so proven years to base it's design off of.

Dave did what he did and he made a good choice. The 4L80E is everything all automatic overdrive transmissions wish they were. Ok, then came the Allison light truck transmissions, but that's another story...and again, a later design that had the 4L80E to match and top. The point of the thread is to inform others they better have some funds ready for "incidentals" over and above the cost of the trans.

[Robznob11]

Ok y'all I'm really not bashing. You are correct in that it's going to cost money to install a 80 E in something it never cam in. My point is that if you choose to do that why spend a fortune on adapters and stand alones when the same money will update the heart too. I get some people like original I never understood it because I like to drive vehicles not just look and brag that it's numbers matching. I have never seen his truck , I don't know how original it is but if he is willing to change gears and update to a 80e or gear vendor that just went out the door any how. Even if I had a perfect truck numbers matching I would dump an odd 402 for a 454 or bigger. Why stick with hard to drive suspension, less than average brakes, etc. You can have old school look with all the comforts of a Cadillac or with the performance of a race car so why settle for less? Gm came out with a lot of good stuff but most all can be made better that's why we have people like foose, Boyd, and many others paving the way.

[The Chainsaw]

Please don't pay a couple thousand to install. It will take a competent mechanic a day at most to toss it in. I have installed a few of them, and it really isn't a big deal. I haven't met anyone who regretted the swap despite the cost.

But no it isn't cheap. Which controller and tps kit did you get.

[davepl]

Originally Posted by kwmech

At that point, money spent on a Gear Vendor you'd be ahead of the game

I would only consider one if it shifted automatically, smartly, and silently. Like a transmission does. But I have no idea.

I know I don't want a switch or to think about it when I go on the highway, that sort of thing.

[davepl]

Originally Posted by Robznob11

I like the gear vendors idea, but even better than that just sell your engine and get a lighter, more efficient bad a$$ ls motors and use stock computer! You will be way ahead of the game. These ls engine's can and do hang with big blocks every day��

That's what I'm doing this very moment in the other stall with my '69 Camaro RS/SS 396 car. Out goes the ZZ502, in goes the LS3. Manual 5-speed though.

[davepl]

Originally Posted by The Chainsaw

Please don't pay a couple thousand to install. It will take a competent mechanic a day at most to toss it in. I have installed a few of them, and it really isn't a big deal. I haven't met anyone who regretted the swap despite the cost.

But no it isn't cheap. Which controller and tps kit did you get.

Installing the trans is easy. Until...

Oh wait, the stupid bolts that hold the crossmember can't be taken out unless you jack up that freshly painted cab.

And the transmission's no good without a computer, so you need to install and wire the TCU module.

But the TCU module can't work without a throttle position sense, so you need to install and wire the TPS module.

But the TPS and TCU module aren't enough, your speedo won't work, so you need an SCU module and motor.

So you need to install and wire the SCU module and integrate it into the factory speedo.

That's what's going to add up, not the time on a trans jack. But everyone rounds down when its their car and rounds up when they're the tech!

Three days is 24 hours labor is $5,525. Hopefully he can do it quicker than that, but that's what it would take me I'm sure if I hadn't done that setup before, which he likely has not (he's slow but near perfect in his slowness). That's not a quote from them, it could be more. It could be less. But in my experience I think 3 days is close.

Now I know I'm going to get the "My buddy bubba will do it for $400 and a case of Ranier Beer" but I don't want my truck scratched, or TPS sensors mounted in view, or wiring with modern crimp connectors and zip ties, and so on. I'm picky.

[Steve Cole]

Hey Dave,
If you can, try to find a guy who will "flat rate" the labor for the install. A $$$ number you can live with. That way no surprises.
Good luck and keep us posted!