If a commercial motor vehicle is equipped with a glider kit that is newer than model year 2000, but the connections and motor vehicle components (such as the engine) are older than model year 2000, is the vehicle exempt from the ELD rule?

No. ELD use is required for vehicles whose VINs reflects a model year of 2000 or newer. The ELD rule requires a reasonable proxy for this data if the engine control module (ECM) or ECM connectivity does not provide it. If the currently installed engine does not support an ECM to obtain or estimate the required vehicle parameters, then the operator must use an ELD that does not rely on ECM connectivity, provided that the accuracy requirements of the final rule are met. See Appendix A to Subpart B of Part 395 section 4.3.1 of the ELD rule for accuracy requirements.