Took over a 401(k) plan in late 05 - we restated document effective 1/1/06. Just notice that both documents (1/1/04 & 9/16/05) from prior administrator did not name a trustee. What are the ramifications of this? How should it be handled? Or is it not a big deal? Please advise.

Is anyone named by the minutes? Who has been acting as the trustee? On the bank/brokerage account? On Schedule P?
My guess is that there is a trustee, whether properly named or not. Your document should so reflect. I don't believe that any remedial action is needed, although the 2005 year may still be in its remedial amendment period.

SPD has to identify trustee, I believe, so be sure to check that.

We had a similiar situation earlier this year. A takeover plan had no named trustee( not in adoption agreement, spd, corporate minutes and a schedule P was not filed with form 5500...there was in fact no trustee although business owner had been perfroming trustee like services. We had the client execute corporate action naming owner as trustee and amended document prospectively.

Does the document in your possession have any trust provisions? Or is there a separate trust document that you haven't received?

The trustee should have been named in the adoption agreement. It is a Corbel plan.