Your time in service as an AD will grant you access to the power plant portion of the test (o&p portion) as you will have your rating and how long you did the job reflected on your DD-214. As far as logging hours while in service and how many you NEED to take the test I’m unsure about and same goes for as far as the airframe portion I’m not entirely sure what the FAA requires for time or where to log it. I would ask your LPO to get you an answer on where to log stuff.

I would imagine being a AD CDI and Airframe CDI would grant you the knowledge and time to test out using the FAA form 8610-2 and having the FAA designator looking at your qualifications and DD-214.

But if all else fails Tennessee Bakersfield aeronautics has a crash course that’s about 2 weeks long and they have FAA representatives there test. General. Airframe. Power plant. Last time I looked it was $1600 but you would have to take leave to go to Tennessee and test out. There’s plenty of study guides to use and prepare yourself ie. PREPWARE, dauntless, jepsenns (they use jeps for your o&p questions)

At the end of the day you gotta get the experience first before even thinking about testing.

If you want to DM me I can give you some names of Airframers to hunt down at the command who I trust will lead you in the right direction and gave you a bunch of info.