[v8volvo]

Should be a pretty straightforward swap. I also have a crusty '85 TD wagon that is donating its drivetrain to a turbo gas wagon. Mine is an '86, more or less the same.

My main piece of advice: Don't scrap your donor car until you have your swapped car fully finished and on the road. There are many little details that are different from the gassers to the diesels and if you scrap the donor too soon, you will inevitably end up crushing some parts you will find yourself needing later on. Some examples: front crossmember and springs, interior passenger side kick panel (diesel does not have the big intrusive bump where the gasser ECU goes), fuel filler tube and neck (bigger on the diesel in order to accept larger diesel fill nozzles), gauge cluster (for your 1989 you can swap the entire diesel cluster straight in and avoid the issues Steve had with his '92, 1991+ had a different cluster but 1983-1990 all used the same one so with some wiring changes you can use your existing diesel cluster including temp gage and diesel tach with no mods to cluster), and more.

I assume you are planning to use the crossmember from the diesel car? It is different from the gasser so welding is required for the engine mounts if using the gasser member. Using the correct diesel one is the way to go.

Another thing to note: to put the larger diesel rad into the gasser body, there is a plastic knockout panel in the lower core support -- pop that out and the bigger/taller rad will drop right in, no modifications required! I mention this because I have worked on two Volvo gas-diesel conversions, an 87 740T wagon and a 95 960 wagon, that were done by a guy who didn't know this and went to a lot of trouble to cut out the whole lower core support and fabricate a new one to hold the larger diesel rad... when he could have done no work at all, and had a cleaner looking result too, if he had used his eyes and his brain instead of his hacksaw and welder.