That center u joint is very special and most driveshaft shops refuse to attempt....
There is very little play required of the ujoint so most can keep going as long as there is not bad slack in it.....

The center swing bearing is not too hard to replace...just be careful not to beat on it much or damage any parts of the shaft while servicing it.....driveshafts are precision machines that look like simple pipes and can be wrecked easily.....the u joint is a monster that should be left alone if servicable life is left in it....

I would change the center swing bearing and housing after going this far.....

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1978 Yellow 300D (The Mustard Toad)
1980 Blue 240D (The Iron Toad)
1989 Grey Mitsu.4WD Mighty Max Pickup (Needs a Diesel transplant bad)

(Open the pod bay doors HAL)