Homepup

Thanks for the reply. I agreed and went ahead and moved the new brake pieces I'd just put on the old 280Z suspension over to the new 240Z suspension. It was like doing 3 brake jobs at once by the time I removed the old brake parts too. Ugh. So my differential does not have that little rectangular block below the drain plug. Does that mean it's an R180 (I'm guessing by what you described before)?

I'm in a weird situation. I ordered new rear struts for my 1973 240Z (which has been all original on everything I've touched so far) but noticed they don't fit exactly (diameter of the strut housing is larger and the strut nut that came with the new strut is too small). After comparing to a spare rear suspension I picked up, the struts fit on that one fine. I'm guessing that someone must have swapped in a 280Z rear suspension at some point (there's number on the outside, Nissan 55303 N4600 AMPCO Japan) and the spare one I have on hand is the actual one for a 240Z. I'm now debating, do I return the struts I just ordered and pickup some new 280Z struts that will fit (since I've already rebuilt the brakes and seem fairly certain that the rear bearings are ok) or swap out this one for the spare 240Z rear suspension (but I'm not sure of the condition of the rest of the parts in it and I'd have to change both sides obviously but only have the drivers side removed currently)? Are there any downsides to leaving it as a 280Z rear suspension? I notice the strut housing is almost 2 inches higher along with being a larger diameter. I haven't looked to try and identify if the differential was also swapped but welcome hints on how to do so easily. Any issues if it was still a 240Z diff with the 280Z suspension? Would seem odd that someone might swap in a 280Z diff but leave it the original 4-speed transmission.