A surgical fastener applying apparatus for applying fasteners to body tissue. The apparatus includes a cartridge receiving half-section defining an elongated channel member, an anvil half-section, and a clamping lever. The cartridge receiving half-section releasably receives a cartridge and a firing assembly. The clamping lever includes a protrusion in a sidewall which is receivable in a bifurcated depression formed in a sidewall of the cartridge receiving half-section to releasably retain the clamping lever in a non-clamped position and in a clamped position. The apparatus includes a disposable firing assembly and SULU.