ok chevy guys dont let me down!

[FleXXedOUT88]

ok i was planning on using a fresh rebuilt turbo 400 mated to a 203 that i have for my wag build. but i have been thinking and i think i wanna run a 700r4 instead of a th400 simply for the OD. since i do plan on taking it on trips and stuff. for gearing i am gonna use a t case doubler. 203/205. my question is will that 203 be a bolt up to the 7004 or will i have to change stuff? and if so what has to change? i know taht 700r4 did not come with 203 attached to them but im not sure if the spline count is the same or shaft lenght or bolt pattern... any info would be great!

[jeepfan93]

advanced adapters

[Randyzzz]

A TH400 has a 32 spline output, while a 700R4 or a TH350 both have a 27 spline outputs. The 203 came stock behind a TH350, but never a 700R4. To install a 203 range box on a 700r4, you would need the 27 spline box, plus the factory adapter for the th350 to the 203. The 700r4 has a longer output shaft than the Th350, so an additional spacer of appx 1.5" would have to be found, or a custom tailshaft made. I see the spacers from time to time on EBay, mostly as part of a 700R4 replacement kit. I believe Novak or AA has just the tailshaft if you want to go that route.

[Gearhead 1990]

PRETTY sure but not positive that instead of getting a fancy adapter or new shaft for the 700r4 you can just use a 700r4 to np208 adapter and just redril the face of the 203.

EDIT: Just found this on Off Road Design

GM TH700 R4 / 4L60E Automatic Transmission:
The TH700 has the same bolt pattern on the back of the transmission as the TH350 and uses a 27 spline output shaft. Since the TH700 only came with the NP208 or later alum t-cases, it's shaft stickout is a little over 2" in factory form. One difference to be aware of is that the TH700 uses 4 metric bolts to secure the adapter to the transmission case.
There are two ways to bolt to the NP203. They are very similar to the TH350 mounting mentioned above.
1: replace the output shaft in the TH700 with an aftermarket output that sticks out of the case by about 7/8". This makes the output identical to the TH350 and you use a TH350 version NP203 with the 27 spline input and a TH350 to NP203 factory 1" thick adapter plate. This is the shortest method. The output shaft cost is $160 and it is available from ORD.
2: use the factory TH700 output shaft and the factory TH700 to NP208 adapter housing with a TH350 version NP203. You will have to re-drill and tap holes in the NP203 gearbox to be able to bolt it to the original NP208 adapter housing. You may also have to do minor machine work on the input bearing retainer on the NP203.

[Casey]

I'm putting my 700/203/205 together with a replacement output shaft from ORD.

http://www.offroaddesign.com/catalog/trannyoutput.htm

I'm using a 203 and factory adapter from a TH350 w/27 splines.

[Elliott]

I have the 350 adapter and likely a 27 spline input if anyone needs it...

[FleXXedOUT88]

well i have put some rough numbers down on paper for the cost of doing the doubler and im seriously considering the black box insteard of the doubler. i really like what they had to say about it and for another 3-400 why not... so now my question is this. what is the easiest way to attach an np205 to a 700r4

[Casey]

Originally Posted by FleXXedOUT88

well i have put some rough numbers down on paper for the cost of doing the doubler and im seriously considering the black box insteard of the doubler. i really like what they had to say about it and for another 3-400 why not... so now my question is this. what is the easiest way to attach an np205 to a 700r4

The way I mentioned. Swap the output shaft in the 700 and use a 205 from a TH350.

I have one for sale w/adapter.

[FleXXedOUT88]

ahh i see... so waht adaper comes with the 205?

[Casey]

Originally Posted by FleXXedOUT88

ahh i see... so waht adaper comes with the 205?

That's a factory GM TH350/NP205 adapter in the pic. 27 spline.

See the bolt pattern in the face...it's the same as the TH350.

Edit: ok so it's hard to see, but it has the same 4 bolt pattern as the 350 and 700

[FleXXedOUT88]

how much are u asking?

[Casey]

Originally Posted by FleXXedOUT88

how much are u asking?

You could find one locally for less once you factor in shipping.

But, if you can't, PM me down the road.

I've had it for a while. I got the 32 spline case I needed to build the dblr and just don't need it any more.

I also noticed you have a TH400. I'd run the 400 and look for a 32 spline short adapter 205.

They're made of unobtainium, but there's a reason why....

Why the 400 over the 700? Th400 is arguably stronger and cheaper to build. You most likely will not see any gains in economy. No need to swap shafts...

The reason I'm building with the 700 is I had one to use and the shaft was only $160. I'm rebuilding it myself and I'll have around $400 in a freshly built 700 with a few upgrades. I should drop the coin for the 5 gear planetaries, but I'm out of $$ on this rig...for now.

[FleXXedOUT88]

So u don't think I'll see any economy gains outt runnin the 700 over the 400? I heard the OD makes a big diff?

[Casey]

Originally Posted by FleXXedOUT88

So u don't think I'll see any economy gains outt runnin the 700 over the 400? I heard the OD makes a big diff?

In my case w/454/700/203/205 D60s 4.88 gears and 39" tires. I won't see any fuel savings. The rig is going to weigh over 6000lbs even without the roof. Maybe...I have to get it together to find out...

You may see a slight increase, however, not enough to justify the cost of beafing the 700 to the 400 strength.

You have the TH400.

I had a 700 to use and a 27 spline 203, that's how I ended up with that combo.

[FleXXedOUT88]

I see I was just tryin to make it as fuel efficent at possible. I figure with the 383 a 700 and me keepn the 3.73 gears and goin with a black box that it might be able to get some decent mileage maybe 15

[Casey]

Originally Posted by FleXXedOUT88

I see I was just tryin to make it as fuel efficent at possible. I figure with the 383 a 700 and me keepn the 3.73 gears and goin with a black box that it might be able to get some decent mileage maybe 15

Yeah it would with that gearing..depending on tire size etc...

Still not enough to justify the cost. IMHO. Since you have the 400...

Stephen Watson at ORD has been running a built 700R4/dblr behind a 454 and now a 468cu in BBC in his Blazer for many years without problems.

I spent a bit of coin to bring the 700 up to 400 strength. GM didn't offer the big block with the 700R4 for a reason.

[FleXXedOUT88]

Hahaha you make a good point... Well I guess I'll just run with the 400 then... I don't have a tourqe converter for it so by chance do u know if u can put a lock up converted in it?? Or if that is what it had?

[Casey]

IIRC the TH400 was a non-lock-up unit. They had a 'variable pitch' option in the mid 60s, but AFAIK they didn't have a lock-up converter.

[FleXXedOUT88]

Alrighty thanks for all the info!

[wickedwagon767]

I also recommend sticking with the TH400

If the Wagoneer were kept largely stock with only a mild tire size increase you'de see a noticable MPG difference, otherwise as was said, the 700R4 is costly to beef up internally to handle more power and it just doesn't justify that cost to use it with the kind of modifications you're talking about

Now during the 1980's GM offered a TH400-205 combination that is known as the "round pattern" combination. This combination with make it easy to slide a Klune-V inbetween the transmission and transfer case