i know what you're going through. i also needed to replace u-joints on my 3/4 and could not find anyone who had them.

i ended up going to a driveshaft shop to see if they could help me out. while they were checking out the u-joints they discovered that the telescoping spline on the drive shaft had signigicant play. solution? we built a new driveshaft. they did a great job, i will have no trouble finding new u-joints for it (since they used a readily available product) and it looks just like the original. driveshaft and u-joints ran about $120.00. even if you don't need the driveshaft rebuilt, i bet any good driveshaft shop could match u-joints to the existing ones.

as far as the u-joint in the ball. mine was in great shape so i did not have to do anything with that or the carrier bearing. seals/gaskets are still available at napa and some of the vintage parts suppliers. if i remember correctly, i got the seal/gasket kit from grumpy's and all the tranny gaskets from napa.

hope this helps!

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