I had my 1600dp motor worked on by a friend of mine last week and have it back now

I have tried every spare nut in my possession but can't find one that fits! I have been through the 3 repair manuals that I own but cannot seem to find a thread count for the bolts. I really do not want to have to pull it back out to find bolts that fit the threads, does anyone just happen to know the proper nut size?
I have tried fine(which makes sense right?) and coarse...don't see anything wrong with the thread pattern on the studs themselves so I don't think that's the issue.
Any help would be appreciated greatly and might earn you a big gold star!
Thanks!
David Parish
