So after my bust on the 180sx wiper motor I did a bit more research and found that majority of Datsuns of similar vintage shared (or 95%) the same wiper motor. There are some Honda ones you can use and various other things but mint16 on here had some 510 motors for sale so I contacted him and picked up two of those.
You can see they're almost identical except the centre linkage shaft is longer on the Hakosuka one.
I took apart/cut the plugs off and ran some quick bench testing. With old cars it's always better to have more spares than less and it's a good thing too as one of the motors was not as good as the other. One was better than my current one though so I used the not so good one as a sacrifice so I could take it apart without concern and learn about how it all works.
What I learnt initially was how much of a huge pain in the ass these bushes can be, and how much of an idiot they make you feel like.. that is until you work out/research how to get them to stay in their sprung houses. Then you feel like an even bigger idiot, albeit an enlightened one.
This motor (which was the best of the lot) looked like it had some moisture inside it sometime in the past. Nonetheless it worked OK so after giving it a little clean up I re-used that part.
My main quandry was how to get the linkage shaft out and move it from the hako motor to the 510 one. I tried for ages to remove a washer on the outside to pull it out but then thought I'd see if it were possible to remove it from the inside, jackpot!
Once this cover is removed you're faced with this. Pretty straight forward system.
Simply remove that nut, couple of washers and the park position thing and a circlip then you can see this. Just lightly knock out the centre shaft and it pops out the other side. Easily enough to reverse the procedure with the hako shaft.
Better look at the size difference. Bigger is better huehuehuehue
Taking the advice of many, I also tried to lube up this linkage area. I couldn't for the life of me get the washer clip thing off the top but it was quite stiff to move around. I did clean it up and gunked it as best as possible and it definitely made it move more freely.
So after putting it all back together it's not a major improvement but definitely an improvement. Also for some reason the park no longer works despite wiring being the same, the motor just seems to run continually so perhaps something isn't quite exactly the same. Anyway, don't need that so I've not plugged that in for now.
I think definitely for a proper decent upgrade the Honda motor could be the way to go, but I learnt a bunch from this so I consider it a win win. I also learnt that I need a new battery and a trickle charger.