Af Pre Amp (X59-1110-00); Squelch Switch (X59-1120-00); Cw Break In (X59-1130-00); Fm Mic Amp (X59-3000-00) S/No. 705-707Xxxx: K, M1, M2 Fm; Mic Amp (X59-3000-01) S/No. 708Xxxx-: K, M1, M2, W, T - Kenwood TR-751A Service Manual