Warbird Information Exchange

Here is the reg., and if you were originally certified with an electrical system, you would be required to have ADS-Out.
https://www.ecfr.gov/cgi-bin/text-idx?S ... 5&rgn=div8

The FAA’s policy for non-equipped aircraft, which becomes effective Jan. 2, 2020, primarily affects scheduled operators but also addresses general aviation operations.
The FAA said that it is placing the burden for approving non-equipped aircraft operations in ADS-B rule airspace, defined by 14 CFR 91.225, primarily on the aircraft operator—and not on the FAA. “To the maximum extent possible, operators of equipped aircraft should not be penalized or have their ATC services affected by operators who choose not to equip their aircraft with ADS-B Out equipment,” the agency wrote in the policy statement. “Therefore, an ATC authorization allowing an operator to deviate from the equipage requirements of [14 CFR] 91.225 must be requested and obtained prior to the operation.”
The ADS-B rules require that the operator of an unequipped aircraft request an authorization at least one hour prior to the flight. “The policy will preclude an operator from requesting and the FAA from issuing in-flight authorizations to operators of non-equipped aircraft. Additionally…the FAA will not accept requests for authorizations by telephone to ATC facilities. Not all requests for authorization will be granted.”

Duke said he expects the FAA to implement a system to track approved authorizations for non-equipped aircraft, and that the agency will monitor rule airspace and take postflight action against unauthorized aircraft. “The FAA will employ its compliance philosophy here,” he said. “Authorizations may be granted for those owners who need to get into or out of rule airspace to equip. The leniency will only last so long.” Unequipped aircraft that request a lot of airspace authorizations will probably find themselves cut off, he added. “Airspace authorizations are not a substitution for equipping in compliance with the rule.”

“ATC will make determinations as necessary to ensure equipped operators are not adversely impacted and that efficiency of operations is maintained,” the document continued. “Consistent with this principle, it will be difficult for unscheduled operators conducting operations at capacity-constrained airports to obtain authorizations. Given the complex and dynamic nature of operations within this airspace, it is unlikely that ATC will prioritize authorization requests for unequipped aircraft over providing air traffic services to aircraft equipped with ADS-B Out equipment. Unscheduled operators with a need to access this airspace on more than an occasional basis should equip with ADS-B Out to ensure no disruption to operations.
An “unscheduled operator” is defined as any flight that does not meet 14 CFR 110.2’s definition of scheduled operations, including Part 135 commercial operations as well as GA flights conducted under Part 91.

Yeah, we know the reg. The difference is in what the FAA is telling people about how they will apply their "policy" to these aircraft. This is an FAA document:
https://www.govinfo.gov/content/pkg/FR- ... -06184.htm ...