We have a 3rd Party Cost Share Commitment and the 3rd Party has stated that they cannot provide the planned resources and instead want to provide the value of (all or part) of the resources in Cash. Is this allowable?

It depends on the nature of the resources that the 3^rd Party was to provide.  If the 3^rd Party resource is integral to completion of the scope of work, then you may need to renegotiate with the 3^rd Party and/or the Sponsor.  If the 3^rd Party resource is not integral to the completion of the scope of work, then this would be allowable.  As cash cannot be used as a Cost Share Contribution, the cash received from the 3^rd Party must be deposited into the department’s gift or discretionary budget and then expended on items or services that provide benefit to the Award.  Those expenses must then be “tagged” as Cost Share Contributions for the Award.