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700 r4 to t400 swap (pics)

wraenking

wraenking

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if you didnt see my post in the lounge, the bellhousing of my 700r4 cracked when i was wheeling.

i found a turbo 400 out of91 gmc burb and went to look at it and take some pics today.

guy said i can have everything i need for the swap for 250 bucks.

truck is still running so when he is home i will drive it.

what exactly do i need to take for the swap?

right now, i have a sb 350, 700r4 /20? I forget which transfer case

heres some pics (best i could get ) of the turbo 400 and transfer case

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That tcase isn't from a 91. The tag says it is a 208C 2.61 lowrange made in 1985. I would make sure that it is infact a TH400. I don't know them well enough and can't see from the pics to make sure that it is a TH400. A TH400 should have a pan shaped kinda like the state of Texas. Make sure that isnt a TH350.

Harley
 
th400 pan is shaped like texas. need kick down switch and wires from gaspedal with bracket bolted to pedel. then both drive shafts to make it easyer. also best get crossmember for tcase to frake as that one is short mount style and yours might be tall mount style. and 91 will be electric speedo vers your cable speedo. . is that your tcase or his. if his its not origanal as it says 85 ish for build date not anyware near the 90 or 91 the burb is. plus you need the vac line from intake to modulator. tcase shifter rod as it might be longer on the 400 than your combo you have now. and the indicator in the dash for the gear position will be 3 speed vers 4 speed now easy to change . that will be about it.

p.s. the rpo sticker dont show g80 so no gov bom in rear end mostlikly .
 
so are you saying this pan does look like texas from what you can see?

and is the np208c bad to use in that setup?

thanks
 
looks like a 400 to me Tom.. Your definitely gonna wanna take the t-case, adapter, crossmember, shafts and torque rods too..
 
rear shaft wont do me any good (suburban) and i dont think the front shaft was there. what are the torque rods?
 
The rods that where missing on the current setup that run over to the motor..

also, what gears did that 3/4 setup have? 4:10?
 
nah, sorry, I meant the 3/4's currently in your truck.. 4:10's right?
 
alright, well, you need to keep that in mind going to a 400 cuz your losing that overdrive...

don't have my gear calc link handy, but you should probably be at decent rpm's with 4:10's..

and hey, keep me in mind if that rig has 3/4's available...
 
the 3/4 tons are available. and for the price im getting on everything for the tranny swap, im sure they are at a decent price. shall i ask and see what he says?
 
mouse said:
Pretty sure the 400 won't have a vacuum modulator. Thats a 350 thing.
Click to expand...

400's have a vacum modulator. Thats definelty a 400 tranny. also you need the gass pedal assembly. just get the whole thing its easier that way. this will have a kickdown on it (electrical kickdown) the vacum modulator controls upshifts. also you can loose the tv cable and setup fromm your 700r4
 
There is nothing wrong with having a 208 in the setup, but I am just making light that it was not the stock tcase. The stock tcase should be a 241. The 241 is a little bit stronger overall then the 208 but not by much. The 241 can be swapped over to a SYE kit though which is nice for later use if you wanted to go that route.

You probably don't want the 241 from a 91 unless your truck is a 91 because the 91 year model used an electric speedo setup instead of a mechanical. If your truck is a mech speedo then you can hook the mech speedo up off the 208 and have a working speedo.

Harley
 
Maybe you guys know, has the trans case been tapped for the aly convertor cover? I thought only 700's had the struts.
 
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