Yes they are, but the brackets appear to bolt into the top of the engine. Never had a reason to take it apart, but to tighten the belts, it isn't a traditional swing bracket on either one. Also, when you look at where it's bolted on, it's on the sides, not the front or back of an alternator tang/bolt eye/hole/traditional mounting.
Nothing on the top of the six-oh is similar to the 7.3, so I'm assuming... I know, I know... that there is a bolt pattern to receive these mounts on top of the engine. They are definitely cradle style mounts though. Very solid, if not annoyingly tight. When I get home, I should see how they're tying the two together, where the combiner is located. On boats we use them to tie two engine alternators into a multi-battery system. They may work on the old IDI's too, no trons to fool with in placing a foreign electric part into the system.
Edit- do you want my VIN in case the thief doesn't know what you're talking about? I'll have to get it later tonight.