The more I dig the more I find...
RPM case with 12 75mhz fm crystals.
Four channels...65,67,86,and 88.
65-one transmiter and two rcvr.
67-one trans and three rcvr.
86-one trans and two rcvr.
88-one trans one rcvr.
$60 for all, free next day air shipping with PayPal.