HI All - First assist post for me on this site. I recently bought a 69 442 and have started work on it. It has a swapped 455 motor and TH400 tranny. The rear axle appears to be original to the car and is a Type O with a 3.23 gear set. The pinion seal has a decent leak and needs to be replaced so I started the process over the weekend - did not get very far. I got the straps pulled off of the u joint but could not get the driveshaft pushed into the transmission to allow for its removal. With a pry bar I could only get it to move about .020 - obviously needs more than that. I have the car up on a lift - are the wheels hanging down pushing the driveshaft into the transmission and jamming it up? TIA for any help!! Here are a few of pics:

 

With the wheels hanging down the driveshaft yoke is pulled out. You should be able to whack the driveshaft with a rubber mallet and drive it forward to disconnect it from the pinion. There is probably crud in the splines. It also a good time to do ujoints if needed.

 

That yoke looks awful close to the tail housing if it’s in the pulled out position

 

Maybe I'm wrong, but it seems with the wheels/rearend hanging down the arc of the lower control arm travel pushes the driveshaft forward. If I am correct about this, then compressing the rear suspension (lifting the rearend) would provide the most clearance.

 

I had to change the yoke in my TH350- 71 Cutlass. I found all the replacement yokes were aprx 1/2" longer. I bought one anyway, expecting to have to shorten it somehow... I tried it and found I could use it as-is. Only thing was I had to fight it to get in, but once in it's been ok for years. I know yours is a TH400, but still that maybe what has happened in the past?

 

Agreed, get the car in the air with the rear axle hanging down. The driveshaft yoke will articulate out of the trans. This will allow room to pry the rear u-joint toward the trans and out of the pinion. You could unbolt the shocks to get additional axle drop if needed.
Make sure the shaft length is correct when installed at ride height. If the shaft is too long that will damage the trans. To short is bad as well. But looks like to short isn't a problem for you.

If you get new joints get Spicers, best in the business. Also replace the straps and nuts.
Always use blue removable Loctite on the strap nuts.
Be sure the pinion yoke saddles are clean before seating the u-joint caps into it.

 

Thanks for all of your thoughts! I am going to try to get out to the shop tonight to take a peek and get some additional measurements. Unfortunately the rear axle is hanging down and what I have is shown in the pics. Looks like I need approx 5/8" of driveshaft movement forward to get the back end out of the yoke...but looks like I have less than a half inch left before that square looking feature on the tranny yoke hits the back of the tranny.... I'll unmount the rear shocks to see how much additional movement I can get...

Does anybody know if the tranny output shaft sticks out of the tranny and by how much? (or how much recessed it is?)

 

The output shaft is proud of the tail case. Has to be at least 1/2"
That shaft went in it has to come out. I would be very concerned that the length is too long.

https://www.dennysdriveshaft.com/

See Dennys site for proper drive shaft measuring procedures. Give him a call with your measurements. He'll know exactly whats goin on.

 

Thanks DrOlds for the Dennys site ref....I agree with you - I think it is too long also. I don't know how they got it in there and hope that I don't have to disconnect the rear axle to get enough clearance...

 

Try unbolting the trans mount and jacking up the trans. It might buy you just enough.

 

Drum roll please! FUN71 wins the $1000 question with the correct answer being I found that by jacking the rear up I could get enough clearance to get the driveshaft removed. I had to go to about 3" before full travel up to have enough room to remove. So looks like tires on the ground there is approximately 5/8" of axial play. I also measured the driveshaft length - it is 49.125" center to center. Should I be worried that with the axle in full down travel the driveshaft is compressed between the companion flange and transmission output shaft with only approx .020" axial clearance? I'll confirm this with the Denny's driveshaft site....

 

Only if you're planning to do Dukes of Hazzard style driving...

Seriously, the rule of thumb is about 1" of clearance with the suspension at ride height.

 

Good job Fun71. I put the mental picture in my mind and it said more room as the axle is lowered. But I believe you are correct it actually pushes toward the trans if lowered below or raised beyond a certain rotational angle in both directions.