I know someone in this site has done a 700r4 swap into a k5 blazer or similar chevy truck before, please share any info you can and any probems you encountered and how to fix them.  My 78 blazer with th350 and np203 leaks from the transmission and t case so when i take the crossmember and t case out to service t case i want to also swap in 700r4 and never have to mess with my transmission/t case/crossmemer for a long time, please help any info is apreciated      

the swap entails a new output shaft and adapter to hook up to the 203. using a 700 and a 208 or 241 it is a bolt in process with no tricks. the 208-241 are nearly as strong as the 203 provided a skid plate is bolted to the crossmember to protect the aluminum case, may also be cheaper than the purchase of the adapter, output shaft, and labor of the shaft installation, a 700 is not a good tranny to go tearing into unless you've had a few of them apart. it requires a special tool to remove the center support.  

oh thaks mud so thats the main problem, i gonna have to go junkyard searching for a 208 or np 241 whichever is cheaper or in good condition, but ive heard that the tv cable has to be ajusted right to make sure trans runs at correct pressure and dons't kill itself. i don't really know what tv cable is so any help is appreciated  

the tv cable is a key part of the 700, they are fairly cheap and are easy to set correctly.

you may be able to find a 700 with a 208 together cheap, the last one I bought was only a $100, that is a rare find, the trany was toast but only took about $90 worth of parts to fix.  

BTW, The "TV" stands for Throttle Valve and it is not that hard to adjust and the THM350 off which the 700R4 was based also has a TV cable too. It attaches to throttle level bracket on carb or TBI unit.  

So is this a pretty easy swap?  No other hidden surprises? WHat year did chevy start using 700r4 in trucks?  How can i identify it, im going to junkyard this weekend to try and find tranny and hopefully t case either 208 or 241 btw why did chevy swicht form 208 to 241 if both are aluminum and chain driven whats the diff vetween the two?  If i swaped the axles in my truck i should be able to do this swap too right?  

They started in 81. There is two basic version of it 81 thru late 84 and late 84 on (though there was a minor valve body revision in 87) Early one have a 27 spline input to tranny. STAY AWAY FROM THEM!! You want a later model with a 30 spline input.   BTW you want a 208, GM when to 241 when they went to IFS and changed the location of front pig to drivers side. YOu need to add a vacuum swicth and relay added to intake that unlocks converter in OD and drive under heavy throttle and when you hit brake pedal but no computer is needed. One more thing, you want a 700R4 with a cast lower torque converter shield as they have a stronger housing to better support Tcase counter torque. Stay away from ones with stamped cover.  

the 241's from the surburban and blazers 88 till 91? drop on the right side so the 241 is still a better option, it is a very easy swap
in 81 gm was also using th350 lockups with the 208 t-case.  

mudb8-.:
the 241's from the surburban and blazers 88 till 91? drop on the right side so the 241 is still a better option, it is a very easy swap
in 81 gm was also using th350 lockups with the 208 t-case.

My 89 burb has a 208 in it.  

I have a 89 burb with a red tag that says 241 on it. they look about the the same, the tag says what it is  

I know they are very similar. The GM went to 241 was it changed when they went to new P/U to get a new outset and also a 241 has a oil pump in it while 208 does not. The whole idea of the pump was to make it less sensitive to fluid level but then they had issues with pump for several years too. The 241 is no stronger than a 208. I would not swap a 208 for a 241 as nothing is really gained. BTW, I know about label and it appears that they had some left over 208's because my 89 has one. There was another change over in 89 as well in 10 bolt. They increased spline count (28 to 30 as I recall) and axle shafts are .1 inches bigger in diameter (no change in bearing area) but the change over was not complete until sometime in 91 so from 89 to 91 you could have either axle size in some models. You can retro fit new axle in a older 10 bolt but you need to change the spider side gears to do it.  

how can i tell the tourque conveter shilds apart, stamped or cast?  I think ill look for a 208 t case since it sounds like its got less parts in it, oil pump,so  i should look for a 84 and up 30 spline 700r4 right?  The t cases were all 30 spline also right?  

the cast is a heavy aluminum cover that is held in place by 6, 10mm bolts, (15mm heads) theres no mistake when you see those.  

Geo450racer:
how can i tell the tourque conveter shilds apart, stamped or cast?  I think ill look for a 208 t case since it sounds like its got less parts in it, oil pump,so  i should look for a 84 and up 30 spline 700r4 right?  The t cases were all 30 spline also right?

There will be no problem telling them apart. One uses a piece of thin stamped metal, the other hast a thick casted cover bolted on instead. Also the 30 spline input shaft I am talking about is the main input shaft into tranny in bell housing not output shaft. BTW, you can retro upgrade a early 27 spline 700R4 to latest spec with a rebuild so if you plan to rebuild it just focus on case type.  

hey guys wat up, i bought a 700r4 trans and 208 t case just yesterday from a junk yard.  THe trans and t case were already bolted toghether and they came out of a 87 k5 blazer.  I noticed the 700r4 has a couple of wires and connectors comming out of it im guessing one is for reverse lights and i have no idea about the others, also about the tv cable, will i still be able to use the downshift cable and bracktrey from the th350?  Is the 700/208 combo longer than the th350/203 combo? it looks like it and i also noticed that the 208 dons't have a yoke at the rear like the 203 does it just has a splined shaft, so im guessing this is called a slip yoke, im probabley going to have to get rear driveshaft modified?  Why are slip yokes bad? ALso one more thing what kind of fluid does the np208 t case take, my hanyes repair book says dexron 2 atf but ive never heard of a t case taking atf, i dont think its thick enough for a transfer case?  THanks for any help