84 c10 chevy silverado 350 ci- 700r4 to a thm350 swap driveshaft problems..

[jkk101]

Ok guys i need some help here badly.I have a 84 c10 chevy silverado truck it had a 700r4 transmission that stopped shifting i checked the obvious quick fixes to no avail.So i had a thm 350 that i rebuilt some time back i figured i would just put it in place of the 700r4.Now here is my problem the tailshaft on the th350 is a 6 inch tail and the 700 r4 has a 9 inch tailshaft .So my drive shaft is 3 inches to short.I took it to a machine shop in town and they said they couldn`t add 3 inches to it without replacing the whole main tubing .They said i needed a longer drive shaft and they could then cut it down to size  no problem and shorten it.I measured the drive shaft i have it is 5` 11 and half inches.So if i added 3 inches that would mean i need a drive shaft that is 6` 2 and half inches.
I have no ideal where to get either a drive shaft that would work but is longer to have it cut down or a drive shaft that is the size i need.So i am hoping you guys can help me and point me in the right direction on this becuase i`m lost .

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Ok i think i know why i am having so much trouble with this.The drive shaft i have now is a one piece drive shaft .I beleave that someone has removed the 2 piece drive shaft and replaced it with this one piece .the drive shaft i have now is 70 1/2 inches from center of U to U and i need one 73 1/2 inches.
Ok so i called to have a one piece drive shaft made but they want 489$ for one and i just don`t have that kind of funds .So i`m thinking of going to a junk yard and finding the 2 piece drive shaft and replacing it.
I see 2 places under the truck that could have been for the carrier bearing the first and last pics is where it looks like someone has cut a bracket out this is about halfway between trans and rearend.the center 2 pics are close to the rearend around 1-2 foot from it.
Does anyone know whitch of these 2 places are for the carrier bearing and whrere i can get the bracket i need to put back in place and a 2 piece drive shaft that will work ?

[454Man]

I'm i'm the same boat I've been riding with a short shaft for bout 5 months check my builds thread for picks of mine

[jkk101]

    ughhh I`m about ready to start pounding my head aginst a wall here.I called a junk yard today and he said he thought he had a one piece drive shaft i could use the size i needed or longer.So i go there and look under one truck and it has the same size driveshaft i already have.
 He then directs me to a van he has full of driveshafts Turns out all where short except one that was also the same size i already have.Spent half the day calling junk yards in and around my area and turned up nothing.I read on the net somewhere that they don`t make a drive shaft any longer then the one i got out of steel that it must be aluminum or it will vibrate.
 I have found 1 aluminum drive shaft on ebay problem is it is 72" 1/4 inches from U to U mine is 70" 1/2 from U to U.So that would be 1" 1/4 short of what i need i thought of just pulling the slip yoke out the extra 1' 1/4 but i don`t know if that would be a wise thing to do .Also i have no ideal what series U joints this thing has.I think mine are series 1310  so that is another problem i could face with this as well .454man i looked around trying to find the pics you mentioned but havn`t found them yet.Here is a link to the drive shaft i found on ebay.

http://www.ebay.com/itm/221044771545?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649

[454Man]

Think its post #19. Sticks in far enough


 http://forum.73-87chevytrucks.com/smforum/index.php?topic=23170.0
Project "BurnEm"

[jkk101]

Ok so i looked at the pic it looks to be around 2" of the yoke sticking out there.Are you running it like that ?Also what size tailshaft is that 9" or 6"?I could kick myself but i never bothered to look and see how much of the yoke was coming out of the tailshaft when i had the 700R4 still in the truck.
  Did you look at the aluminum driveshaft i saw on ebay ?I wonder if that would work or not but i bet i would have to change yokes on the tranny and rearend if the u joints are small or bigger.measuring my u joint caps accross they are 1" 1/16 from cap end to cap end it`s just under 3" 1/4 whitch is 3" 7/32.
 So according to driveshaft masters it`s a 1310 sieries Ujoint.i messaged the seller of that driveshaft and asked the Ujoint size hoping to get a response soon.

http://driveshaftspecialist.com/HTML%20Measure/UJ%20ID%20Guide.html

[454Man]

Now I think about it I think mine is the 9 inch version, but still 3 inches shorter than the 700r4. Not sure of the t tail shaft length will get the measurement in the am. Yes been running like that fora while now with no problems/vibrations

[DnStClr]

You're having a time of it-Wouldn't it be a better idea to have the 700R4 rebuilt and stop worrying about fitting the TH350?

[jkk101]

Well IDK here is the thing i have a c10 69 chevy i took the thm350 out of .I stopped driving the 69 becuase the crank broke .But 4 or 5 months before the crank broke in it i dropped 900$  to have the thm350 rebuilt.So i really think it`s a better transmission and option.Thing is the 69 has set for at least 10 years with the thm350 in it.I have done got the 350 in the truck becuase when i called the machine shop and asked if they could add 3 inches to my driveshaft they said they could or the person i talked to did.But when i took it down there a couple weeks later they said the couldn`t without replacing the whole tube and it could still vibrate.But if it`s going to cost me 489$ to get a driveshaft made then i might be better off rebuilding the 700r4.

[454Man]

Have you tried fitting the shaft in yet?

[jkk101]

Well i know the 700R4 has a 9" tailshaft and the th350 has a 6" so will be 3 " shorter.I haven`t tryed to put the driveshaft back because i figure at best be maybe 1" that would catch on the tailshaft of the trans.I know when your driving hard braking and acceleration will cause the driveshaft to travel in or out of the transmission also if you loaded your truck it would go in further.From what i have read online you run a risk of the slip yoke coming completely out of the transmission and dropping to the ground if too short.If the yoke sets to far in then you could shove the yoke into the tail housing of the trans.But you would have to have the wronge size yoke for that i would think a longer yoke .Or at least that is what i have read online about it but i have also have people tell me they have run with the yoke out 2" or a lil more almost like your setup .
 I`m not sure how much yoke is showing on your but apears to be around 1" 1/2 or maybe 2"?Have you measured how much it is out?

[jkk101]

OH happy day !! i found a driveshaft that should work nicely.It`s aluminum 73" 1/4 from U to U .Mine is 70" 1/2 so that 2" 3/4 longer then mine.I would think just being a 1/4 inch short would be fine.
 The onlt bad thing is it has a 1350 series u joint so i will have to buy a new slip yoke and rearend yoke .I might get the slip yoke with it but i don`t know if it`s 27 spline like mine.But i hope to be
up and running soon .

[454Man]

Good luck. My shaft is Abbott 2-1/2 inches short

[square81]

I had a 81 c10 which I swapped in a 700r4 in place of the turbo 350 and used the same drive shaft with no problem so there shoudnt be a problem.

[jkk101]

I had a 81 c10 which I swapped in a 700r4 in place of the turbo 350 and used the same drive shaft with no problem so there shoudnt be a problem.

 That would depend on the talishaft lenghts.My 700r4 had a 9 inch tailshaft and my th350 only has a 6 inch one .Some th350`s have a 9 inch i wish mine was a 9 inch then i wouldn`t be going thru this.

[square81]

Yeah thats right, i cant remember the length of the th350. I'd try and find a one peice, only because I hate 2 peice driveshafts, had problems with them.