Looking at this adapter for the 4R70W and also the adapter for the 6R80. Do these adapters install form the outside of the trans or do you have to gut the trans and install the from the inside?

Depending on your Donor transmission and choice. The 6R80 adapter is for the 4 wheel drive transmission only. There are 4R70 kits for either the 2wd trans where you do need to go in, or 4wd, adapted from outside. Transmissions from 4 wheel drive donors are easiest to adapt to the Early Bronco.