A number of Nixon's henchmen were tried, convicted and sent to prison while Tricky was allowed to resign without facing trial and with full post-presidential benefits, which are very generous. I guess Ford didn't buy into the notion that no man is above the law. I'm almost certain there was a deal struck that allowed an unknown congressman to become VP, Nixon was corrupt and sleazy but he was no dummy.
No doubt Trump is vetting his own Gerry Ford to throw his weight behind come election time, they're already trying to "out pardon" each other.