Insurance and death benefits payable to testamentary trustee.) A person having the right to designate a beneficiary of benefits payable under any insurance, annuity or endowment contract (including any agreement issued or entered into by an insurance company in connection therewith, supplemental thereto or in settlement thereof), or the right to designate the beneficiary of benefits payable upon or after the death of a person under any pension, retirement, death benefit, deferred compensation, employment, agency, stock bonus or profit sharing contract, plan, system or trust, may designate as a beneficiary a trustee named or to be named in his will whether or not the will is in existence at the time of the designation. The benefits received by the trustee shall be held and disposed of as part of the trust estate under the terms of the will. If no qualified trustee makes claim to the benefits within 18 months after the death of the decedent or if within that period it is established that no trustee can qualify to receive the benefits, payment shall be made to the representative of the estate of the person making the designation, unless it is otherwise provided by a beneficiary designation or by the policy or other controlling agreement. The benefits received by the trustee shall not be subject to claims or other charges enforceable against the estate or to estate or inheritance taxes (including interest and penalties thereon) to any greater extent than if the benefits were payable to a named beneficiary other than the estate of the person making the designation, and in the case of benefits which otherwise qualify for exclusion from the gross estate for federal estate tax purposes, such benefits shall not be used by or for the benefit of the estate of the decedent.