Here's what the service manual has to say about the injector pump diaphragm:
It says the recommended oil is "genuine Datsun or equivalent"
If there are any other pages you'd like to see, just let me know.
I think 1000-1500 is a fair price if it runs well. These are good reliable little trucks that are easy to work on with a few basic tools. I've got an '82 4x4 as well and it's needed absolutely nothing other than oil and gas over the past 5 years. Honestly, you'll be hard pressed to find a 1982 anything for $15oo and no rust. Especially in a place that has winter.
I've heard quite a few people recommend Chevron Delo 400 for older engines based on its additives. Apparently it's better at protecting our cams from wear as opposed to most regular oil for modern engines.
I have 235/75/15. At stock height I wouldn't want to go any bigger. With cranked torsion bars 31" tires should fit, but may rub (and you'll likely need an alignment)
I think it would be a great project. If you do it, please keep us posted. I don't think there is a better nissan diesel for this application and the fact that you have access to one makes it even better!
Truck has really come along. How is she for power with the carb/headers/cam and the bigger wider tires?
Is that snow in Texas? Talk about a cold day. Was is declared a state of emergency?
Speaking of snow here's how my poor 720 sits for the moment. I'm sure Sealik can relate.
This thread talks a little bit about it, but I don't know if it will answer your question: http://community.ratsun.net/topic/47967-nissan-hardbody-frame-vs-nissan-720-frame/