Don’t you have access to Morningstar or some other annuity hypo program?  A program like that should be able to give you that info.  You could also try calling Principle to see if they have specific info on that contract available for downloading or emailing. 

Not sure if all of the group annuities from Principal are the same but the couple I’ve seen have an average expense of 2%

Principal can literally price a plan fifty different ways on their FIA platform.  You will need to sit down with the plansponsor and have them login to the website and review the investment options.   Some plans have a flat management fee on top of the expense ratios.  Other plans have both calculated so you don’t see the investment management fee unless you can look at the original contract.  Remember too that if there is no hard dollar cost the client is probably paying a basis point fee per active particpant.  You are going to have to get the docs, or have the plansponsor get a copy if they have lost it.  Good luck and happy hunting.