Im pretty sure it is a fixed-shape IRF but I copied my 3dDeconvolve code for you to see just to be sure. Thank you Gang!
3dDeconvolve -input ${subj}_${run3}_norm+orig.HEAD \
-num_stimts 4 \
-stim_times 1 stimuli/mf_memboth 'GAM' \
-stim_label 1 mf_memory \
-stim_times 2 stimuli/ff_memboth 'GAM' \
-stim_label 2 ff_memory \
-stim_times 3 stimuli/nf_memboth 'GAM' \
-stim_label 3 nf_memory \
-stim_times 4 stimuli/fa_memboth 'GAM' \
-stim_label 4 fa_memory \
-iresp 1 ${subj}_${run3}_mf-norm-irf -TR_times 0.575 \
-iresp 2 ${subj}_${run3}_ff-norm-irf -TR_times 0.575 \
-iresp 3 ${subj}_${run3}_nf-norm-irf -TR_times 0.575 \
-iresp 4 ${subj}_${run3}_fa-norm-irf -TR_times 0.575 \
-full_first -fout -tout -nobout -polort A \
-concat stimuli/TR.1D \
-progress 1000 \
-bucket ${subj}_${run3}_stats