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Transmission ?


Hurley

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I have a 72 521. I put a 4 speed in it from a 510,but it doesn't have the threads for the end bolt. I took the end off the origional trans. Will I be able to run the drive shaft without the end bolt to the trans?

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You'll have to weld up the bolt hole in the flanged adapter, or the oil will run out through the U-joint flange.

That makes sence. Do you know the reason why they made the trans end different on the truck? Thanks for the reply

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No idea why. They used the regular slip-yoke in the 320 and 520, even the early 521 (68-69). The slip part went into the driveshaft in the 70-72 521, then back to the normal slip-yoke in the '73 620. They probably thought that the carrier bearing wouldn't move enough to allow the front shaft to move with axle travel, but obviously it did since the 620 has a carrier bearing and the slip yoke.

 

The 510 (and the 320 and 520) had the one-part driveshaft, so the slip yoke was necessary.

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No idea why. They used the regular slip-yoke in the 320 and 520, even the early 521 (68-69). The slip part went into the driveshaft in the 70-72 521, then back to the normal slip-yoke in the '73 620. They probably thought that the carrier bearing wouldn't move enough to allow the front shaft to move with axle travel, but obviously it did since the 620 has a carrier bearing and the slip yoke.

 

The 510 (and the 320 and 520) had the one-part driveshaft, so the slip yoke was necessary.

 

I put the freeze plug in the flange on the tranny shown above. The flange is there to adapt the 79 200SX dogleg transmission to the 521 driveshaft. I unbolted that flange from the 521 tranny, pulled it out, slid it right into the tail of the dogleg and tapped a freeze plug in there to keep oil from dripping down past the splines. I have put several thousand miles on it and not spilled one drop of tranny fluid.

 

Oh, and its a 40mm freeze plug, BTW.

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The 521 used a two piece drive shaft with a splined slip joint on the rear one. Didn't need the tranny one?

Is the splined slip joint adjustable. The drive shaft is about 3/8s of an inch too long when I tried to hook it back up today. I got the drive shaft from a different 521. So I thought it might be adjustable there.

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Is the splined slip joint adjustable. The drive shaft is about 3/8s of an inch too long when I tried to hook it back up today. I got the drive shaft from a different 521. So I thought it might be adjustable there.

 

What was wrong with the original driveshaft? I'm pretty sure the 521 and 510 transmissioms are the same length. Hmmm...... :confused:

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What was wrong with the original driveshaft? I'm pretty sure the 521 and 510 transmissioms are the same length. Hmmm...... :confused:

When I bought the truck it came with l16 with auto trans and 4 lug rear end from a 510 wagon. Auto trans was 31 inches long. I found a 521 that someone had stashed in the back of there driveway. I knocked on the door and asked if they wanted to sell it. He said $300 and its yours. Body is straight with minimal rust. Truck runs and drives, but only on 3 cylinders.

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