Carby to manifold bolts

[Hoogah]

Just picked up this Tilly and manifold at a swap meet and notice that the bolts holding the carby on have nuts. My Zenith doesn’t. Did all Tillotson carbs have nuts on the bolts or was this one done out of necessity? How many of you have gone down this path with either type of carb? I ask because one of the threads in my Zenith is weak and I’m going to have to do something about it soon.
(Sorry, the Zenith photo is sideways and I can’t fix it.)

Additional edit, 9th April ‘18: My Tillotson is actually a Marvel Schebler. Thanks for the correction, Duke36.