The Convair XSM-74 was a sub-sonic, jet-powered, ground-launched decoy cruise missile.
He says "it is at least possible (but in no way certain) that 'LR85' is an error for 'J85'," noting that the contemporary GAM-72 Quail and XSM-73 Goose were both turbojet powered, and that one source refers to the GAM-71 as turbojet-powered.