# Measuring Drive Shaft (opinions needed)



## rbpwrd240 (Mar 19, 2007)

Howdy gang, 

Its been a long time since my Dad and I have been able to work on the GTO. Work, Family and other projects have all stood in the way but now with my father being retired and me running my own business's from my home we can finally sketch out some time to work on the car together. 

We started to pull out our baskets of parts and when we got to the drive shaft, a quick debate started about which drive shaft was the correct one. 

So here is the situation.

We have three drive shafts two measure 58.5" and one measures 61.25". When I measured the length from the center of the slip yoke joint to the center of the u joint on the rear end I got a measurement of just over 61.25". Now I understand that when you measure for a drive shaft the car needs to be on the ground but currently that isn't possible due to the front end being torn apart. so this is more of a hypothetically speaking situation.

To me I think the 61.25" drive shaft is the correct one for our 455 four speed. As the other two seem to be too short. I understand a little shorter is good due to play but two inches seemed like a lot to me.

Well, what do yall think?

Thanks,
Alex R.


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## PontiacJim (Dec 29, 2012)

rbpwrd240 said:


> Howdy gang,
> 
> Its been a long time since my Dad and I have been able to work on the GTO. Work, Family and other projects have all stood in the way but now with my father being retired and me running my own business's from my home we can finally sketch out some time to work on the car together.
> 
> ...


The TH-400 is slightly longer than the 4-speed, so the longer shaft is probably what you want. You want to make sure the trans yoke is not bottoming out up against the trans and yet not pulled to far out so it does not fully engage the splines as needed. You should have about 1" of space between the two as measured WITH the weight of the car on all 4-wheels as it sits on the ground.


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## Pinion head (Jan 3, 2015)

OEM stock length driveshafts, measured center to center of u-joint.

'64-67 Pontiac A body 
w/ Pontiac V8 & small output shaft Muncie 4spd, OR Super Turbine 2 speed auto: 60.00"

'67 GTO with short tail Turbo 400 & correct med length '67-74 T400 yoke: 59.375"

'68-72 Pontiac 2 door A body 
w/Pontiac V8 w small output shaft Muncie 4speed or ST-300 or Turbo350: 56.00"

'68-72 Pontiac 2 door A body w Pontiac V8
w/ short tail T400, OR big output shaft Muncie 4 spd, OR '74.5+ 2nd Design BW T-10: 55.375"

Note: 
-Factory 3 speed equipped cars took their own length driveshaft during these years. 
-there are many different length "T400" driveshaft yokes, substituting a "long" version or the very late '75-76 and later style, can cause fitment problems. As an example, a '70 T/A factory equipped with the "long" turbo 400 yoke takes a shorter driveshaft than same equipped '71-74 T/A. The long Turbo 400 yokes also were used in certain BBC pickups and Chevelles. Pontiac, 99% of the time, used the medium length 3R Turbo 400 yoke.
-'64-72 Pontiac Abody that has been upgraded to the 8.5 A body rearend, will require shortening the stock length driveshaft 7/8-1"


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## Herding Goats (Sep 16, 2017)

*Great driveshaft info*



Pinion head said:


> OEM stock length driveshafts, measured center to center of u-joint.
> 
> '64-67 Pontiac A body
> w/ Pontiac V8 & small output shaft Muncie 4spd, OR Super Turbine 2 speed auto: 60.00"
> ...


Can confirm the stock 1970 GTO short tail TH-400 driveshaft length works with big output shaft Muncie 4 spd (1974 M-20) installed in 1970 GTO (A Body). Thanks for the info Pinion Head!


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