Final drilled all nutplate holes. Assembled seat rails to each other and match-drilled the common holes. Assembled seat rails and bulkhead sides to the carrythrough and match-drilled the common holes. Trimmed the end of the hat stiffeners and then cut them apart, clecoed them to the assembly, and match-drilled the common holes. Drilled all bolt holes for AN3 bolts. Assembled the F-1004-J pieces using temporary AN4 bolts and drilled the #30 holes. Countersunk the forward face of the #30 holes and all #40 nutplate holes. Began deburring of all the part in preparation for riveting.