T400 to 4L80e or 700r4?

[Kamloops83GMC]

So I have this 1987 crew cab 4x4 350TBI with a T400, np205 tcase, and I would like to have an overdrive transmission

I have two donors:
First one is an 83 single cab 4x4 350 with 700R4 and 208tcase.
Second is a 1991 crew cab 2 wheeldrive 350TBI.

Which would be better?

Anyone do this swap before? Is it painless or a pain?

[meatwagon83]

costs more to do but a 4l80e is stronger

[mud.man.rj]

x2 on the 4l80e, way stronger and will last a lond time with use and abuse.

[Ziegelsteinfaust]

I vote 4L80 as its tough as nails stock, and a T700R4 needs big money to equal it.

Both are about the same from the people I know who have done it. Its either computer or cables, and for myself I would go 4L80 with a truck as big as yours.

[cleansquare]

I just did a 4L80e swap. I bought the standalone computer from TCI for 600, the cable-x box that converts the mech speedo to electronic for 300 and the tps kit for 120. had the 4l80e completely rebuilt for 1600. Put it in place of my TH400

[andrewmp6]

What about adding a gear vendors? http://www.gearvendors.com/

[meatwagon83]

Originally Posted by andrewmp6

What about adding a gear vendors? http://www.gearvendors.com/

3k thats what about it

[andrewmp6]

cleansquare spend 2620 for his swap 3k is 380 bucks more tho.

[Rogier]

Originally Posted by andrewmp6

What about adding a gear vendors? http://www.gearvendors.com/

Great as a combo with a TH400, but as said before: price is not worth it.

700's are nice, but only if you do not pull anything, never go into the mountains and have a weak motor. Even with transmission performance parts, I've cooked some.

[bilfman]

I did a 4l80e swap. Was not hard at all. Here is the link to the build.

http://67-72chevytrucks.com/vboard/s...d.php?t=537481

Now if you get lucky you can find a 4l80e factory mated to the np 205, such as in my case. These were only released in 1991 1 tons.

[Kamloops83GMC]

I'm on a budget, I only have the 1991 4L80E or the 83 700r
The crewcab has a NP205 tcase and has a speedo cable, while the 4L has VSS. Do I need the VSS for information to run the 4L?
Anyone know if the splines on the two wheel drive 4L will mate with my 205 tcase?

[ivorton74]

4l80 is way better. I've heard the early 700r4s are no good.

[kevinr1970]

Originally Posted by bilfman

Now if you get lucky you can find a 4l80e factory mated to the np 205, such as in my case. These were only released in 1991 1 tons.

I have seen '91 Suburban 3/4 ton 4x4 with a 4l80 tranny, not sure what transfer case it was though?

[99monte]

91 4L80E is in a 2wd truck? That sounds like trouble,don't they use a different output shaft between 2 & 4wd?

[Kamloops83GMC]

Anyone know how many splines on the output shaft on a 91 4L80E two wheel drive?
What about the input on a 87 205 Tcase with T400?

[Rubble]

Just mt thoughts here,but if you already have the 700R why not get it rebuilt & use the 208 combo?? One of our mechanics used to work at a tranny shop & he told me if a 700r was built right it would survive quite well.Don't tow in OD & put in a tranny temp gauge.This would be your most economical route since you have all the parts now.Far as the 208 vs 205 it depends how rough your on the truck.I have ran lots of 208s over the years without any trouble.I don't rock crawl with them,mostly snow & mud getting into wells.
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[Rubble]

Another thing to look at too is why are you needing OD? If your not putting many Kms on your truck in a year,maybe it might take a while to even pay for the swap.I would sit down & pencil out your yearly Kms,estimate what you r gas costs are & then see if the swap is even worth it.Something else to think about unless your 400 is toast already....
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[pwradder]

i agree with rubble, in youre situation the 700r would be youre best bet depending on the use. if you've got a good one to use and you dont beat up on it, it'll hold up just fine behind that 350 tbi motor. i've got a rebuilt and upgraded 700 behind a healthy big block with a 208, the rebuild cost me $1600 and it's holding up great.

[Kamloops83GMC]

I want OD for fuel economy because pretty much anywhere you go around here its highway driving, and the engine won't last at 3000+ RPM.
The last truck I had with a T400 was getting a staggering 6 Imperial MPG with 3.73 gears.
Before that I had the 83 GMC with the 700r4 and 13-14 IMPG was the norm. And the engine just purrs on the highway.

Anyone out there swap a 4L80e in place of the T400?

[Mr. 250r]

the 91 suburban 4l80s have the np241 behind them and good luck finding the 91 4l80 with a 205 might win the lottery first lol