coolchevy,
In conventional fasteners, there is no 3/4 X 12 TPI configuration. 3/4" utilizes 10,16 or 20 threads per inch.
This isn't to say they don't make a 3/4 X 12 thread, but it must be something weird and special. Are you sure you measured correctly. Maybe the end of the spindle is banged up...pretty common.
Stuart
