Abstract: We present C I(21) and multi-transition C-12 O observations of a dusty star-forming galaxy, ACT J2029+0120,which we spectroscopically confirm to lie at zeta = 2.64. We detect CO(3-2), CO(5-4), CO(7-6), CO(8-7), and C I(2-1) at high significance, tentatively detect HCO+(4-3), and place strong upper limits on the integrated strength of dense gas tracers (HCN(4-3) and CS(7-6)). Multi-transition CO observations and dense gas tracers can provide valuable constraints on the molecular gas content an…