Just put my new race car build ('77 w/5spd) on track the other weekend, supposedly "good" drivetrain happened to have issues with 5th gear, reverse, shift lever, leaking, etc.  After a bunch of research on here and the various other incorrect vehicle assembly issues I've discovered from the PO, I opted to do a full rebuild. 
  
Upon inspecting the 5th gear synchro pack (black fiber style), I found these parts inside that synchro pack.  The Thrust blocks both have a symbol that looks a whole lot like the MItsubishi symbol. 
  
Is that symbol normal for this part and it isn't actually Mitsu?   Is this a compatible small part swap?  Or was this a part that looked about right that someone threw in there, which may have some impact on the lack of 5th gear? 
  
This leads me to another question that I have not been able to find searching here or google - are there any cross-car/company part exchanges that work?  Are those pieces even available anymore if I want to put Nissan OE stuff back in?