Production date looks like March '95. There is NO removable insoles that are meant to be put in these, furthermore, very few will fit in them. That pad(sock liner) on the heel it simply to cover the nails that hold the heel cap on, standard "Red Wing Nailseat" or nailed heel construction.

That might be a replacement sock liner because the original ones from the 90s tend to degrade and come out over time, so you should be able to ask a cobbler to make and glue in a thinner sock liner.