Are there any statutory or regulatory restrictions that define who or what type of organizations can spend RDT&E? Why aren't regular units such as 82nd ABN Division or allowed to execute capital investment funds such as RDT&E?
There are no policies in regards to the type of command that can request RDT&E funding within the FMR 7000.14-R.
The Financial Management Regulation (FMR) 7000.14-R does not specify who can request RDT&E funds. The FMR 7000.14-R Volume 2A Chapter 1 distinguishes when RDT&E should be requested as far as items/services. The FMR 7000.14-R Volume 2B Chapter 5 explains each Budget Activity to include different Milestones and Phases which necessitate RDT&E funding. The FMR 7000.14-R is the governing guidance for DOD Financial Management. The US Army may have more strict guidance on commands that can request RDT&E funding.
I strongly encourage you to contact the Comptroller/Legal Office for additional US Army guidance in regards to your question.