In cases where an FAA Form 8130-3 is not available for specific avionics items, the reason is that the items are not TSO'd. According to FAA 8130.21F Procedures for Completion and Use of the Authorized Release Certificate, FAA Form 8130-3, Airworthiness Approval Tag Section 2-1, Paragraph A (Page 2-1) states "Except as provided in paragraphs 2-2 and 2-6 of this order, products, parts, and appliances not produced under an FAA production approval are not eligible to receive a Form 8130-3"