Yes, it will!
From the owners manual in the Members Hangar section:
[color:"blue"] "Additionally the MX300 will directly replace the following NAV/COMM'S:
RT308C RT328A
RT328C RT328D
RT508A RT528A
RT528E
The RT308C, RT328A, and RT528A use pin L of J3 instead of pin BB of J4 to output the NAV demod signal. The MX300 may be ordered with the different output pin or may be modified in the field.
An optional adapter is available which permits the replacement of
the following NAV/COMM'S:
RT517 RT514R
RT540 RT515R
RT515A-1
The MX300 will interface directly with the ARC IN525A Course Deviation Indicator and similar units.
The remote channeling outputs of the unit permit channeling of Glide Slope receivers and DME using the ARINC 2 out of 5 channeling system."
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