Why does the Mk3 use Tripod inner Joint but Mk4 6 Ball Plunging

[alcyon]

As per my title. I noticed the mk3 uses a tripod inner, but the Mk4, IS300 and SC300 which are newer comes with a 6 ball plunging joint on the inner side. Is this actually an improvement ?
I currently have a clunk and i strongly suspect its coming from the inner tripod, and as per recommendation of a friend, I will be switching over to IS300 axles(2 left sides-shorter side) and stub axles.

 

[Bru]

Describe the situations of the clunk. Sounds can come from many sources. I thought I had a bad wheel bearing, which turned out to be the spherical bushing in the rear knuckle. I replaced both sides. Sometimes ring gear backlash can make a sound.

 

[alcyon]

All my spherical bushing are changed to new. The clunk happens whenever i put it in N to D or R, and whenever I suddenly let off the throttle and also when the car is slowing down to a crawl and the auto trans shifts to 1st gear. As you know I rebuilt the diff many times, and even on some rebuilds i went with a very tight backlash, and yet the clunk is still there. Subframe bushings were replaced also. I can feel it coming from the tripod joint area when I get under the car and move it by hand. I replaced the left side tripod joint, but it is very expensive, and It didnt even reduce the clunk, so I am very weary of replacing the right side.
Since my friend said the IS300 axles are better, I decide to give it a try.
This is his car the video. The driveline parts ,susbframe and suspension are all mk3 Supra. I also went to an auto trans specialist and he said its coming from diff or axles.