prolly a 1.5T - LCF's were available in 1.5T's [5100,5400,5700], 2.5T's [7100,7200, 7700] and bigger .... you won't find much info about quantities made, GM didn't keep very good track beyond 'light', 'medium' and 'heavy duty' .... shop manuals cover the dirty details on all models, available at any of the vendors
Bill