Yes, I am sure that if you buy the Johnson lifters, you are getting the very same lifter that comes in the box marked GM Genuine Parts. As far as the other manufacturers I stated being the same lifter, I am only passing on information that was told to me by a reputable GN Vendor... I have a contact at GM that has verified that Johnson makes their lifters. The units sold at the above mentioned site are Johnson and work flawlessly.
Jim