Just checked autohaus, here you go on the intake gasket, USD $3.99 in stock.
https://www.autohausaz.com/pn/1257212
This came up correctly when I searched under 1982 240 GL wagon with D24, but did not come up at all when I searched under 1983 760 D24T. The trick is to know all the different years/models where the diesels were offered and be studious about trying all of them as the "application" till you find what you are looking for, or better yet put together a part number list and search that way. Volvo numbers almost always cross over with no hassles.
My feeling is that *everything* for these engine is still sitting on shelves all over North America, the trick is just trying to help vendors realize they have it and get them to sell it to you.