[Alpines] S-V Wiper transmission chrome nuts question

[WSuman at aol.com]

My apparently original wiper mount studs (the part of the transmission  
that comes up through the cowl) have one galled side.  I procured a  
replacement transmission / motor that appears for all the world to be  identical, but 
the thread size differs from the existing, and from the new  replacement 
nuts from Rick.
 
The replacement threads appear to be 5/8 x 24.  Are there early / late  
versions?  Could this be a non-Alpine part?
 
Thanks
 
Walt
Seattle.