1986 Nissan 720 4x4 - front drive shaft u joints // longevity advice!

[hands]

I recently became the owners of the above mentioned truck, and was pointed to this forum from the guy I bought it from. Have since spent hours looking over old posts here, and have been meaning to make one for my truck and ask general advice from the community about maintaining such a cool vehicle into the 600k+ miles. The truck is in great-ish mechanical shape, 158k miles, 4x4 works excellent, transmission should be good for another couple dozen thousand miles (I hope) before needing rebuilding. I have been going through all the basic maintenance stuff and planning for future upgrades as I'm able to do them, however I have now encountered an issue that has got me fairly stumped:

 

The front drive shaft going from the transfer case to the front diff has smaller u joints than the other two drive shafts, and from what I (and every parts store, and two drive shaft shops, and a 4x4 specialty shop, and two Nissan dealerships) have been able to find, these u joints are not available anywhere from anyone. The first drive shaft guy I took it too is kind of a wizard in finding stuff like that, he ordered three based of the measurements and none of them were correct. I've gone through the parts stores with a fine tooth comb, and ordered two different sets of what seemed by the description to be the smaller, front drive shaft u joints, only to receive boxes of the larger main shaft u joints. So, after much time spent on the phone, on the web, and driving to various auto people, the only solution seems to be to fabricate a new drive shaft with proper sized u joints for around $700.

 

I ask you fine people: is there any other solution to this besides fabbing a new drive shaft? Is ordering one online based off measurements I take a fairly safe bet (i've seen some in the 2-300 dollar range, but I really don't want to buy something that just breaks or doesn't fit)? Are there any other model vehicles that have the correct sized shaft but with 1310 or some other more common u joint sizes that I can potentially find online or at a wrecker yard?

 

I appreciate any advice or information about this truck! I intend to keep this truck for the rest of its / my life, so I want to do the best work that I can on it, however I'm not a financially wealthy man, and a solid $100 repair that will preform as needed is better than a $700, one and done repair to me at the moment.

 

Thanks to all of y'all for the work, knowledge, and energy to keep these trucks alive!