Form your picture those do not look like extension jambs but the inside of the regular window jamb.
Those ar probably replacement windows in old jambs but hard to tell for sure.
Clean the old caulk up ,paint and recaulk as good as you can would be your best bet without spending a lot of money.
Those ar probably replacement windows in old jambs but hard to tell for sure.
Clean the old caulk up ,paint and recaulk as good as you can would be your best bet without spending a lot of money.