What's the difference in these wheel studs?  They both have same thread.  I need the bigger headed ones like in this spacer.  Are the others metric?  I see an M on them.  They were in this ford 60 rear axle when I got it so I used them to mount the spacer.  When I went to remove it, they were all spun and really fun to get out.  Can I get the bigger ones local?