Authorship on a manuscript that has gone through significant changes
I agree with the answer by @BrookeMcKnight.

I would add that, importantly, even if you have made substantial changes, it is your responsibility to reach out to your coauthors and afford them to opportunity to contribute further to the updated manuscript, otherwise you are somewhat stealing the authorship from them.

They may prefer to substantially edit what you have done, to provide minor comments, they may disagree entirely with publication and ask for major revisions or for their name to be dropped, etc - the key is that your responsibility is to give them the opportunity to participate and make those decisions. Their initial contributions did not expire over the 3.5 years the manuscript sat unworked on.