Hi Guys,
So the 6 bolt patter works for the Dana 30 and Dan 44. It's the number of bolts that holds the wheel spindle to the axle knuckle.
When I first got my 66 it had a Dana 30 and when I installed the WH front disc kit I found the shims installed on my Bronco. On one side were crumbled plastic shims and on the other side was a cracked and crusty metal shim.
Later on I was fortunate enough that Chuck from B.C. Broncos was coming to SoCal and I upgraded to a 73 Dana 44. It needed one shim on the drivers side. I guess 40+ years of wear and tear on these axles takes its toll.
Below is a photo of my shim, its the little thin shinny "cleanish" part in the center of the photo. Also is an excellent write up on how to install them from a Jeep site. It's best to get an alignment before and after so you can really dial in the shims. I have the Firestone lifetime alignment which as worked out very well.
Good luck!
PS Personally I'm okay with the Jeep guys because after all not everyone can live the Bronco dream!
https://www.jeepfan.com/projects/castor-camber-shims-install/