They're probably more common than any of us realize. I can think of four recently.
88 V30 454W crew cab Kittery fire truck, for sale now, newly acquired by second owner. Kittery Maine, now Kingston NH
89 V3500 GMC 454W 135.5 chassis cab former dump. Looked at to buy this summer but had a rotted frame. Lebanon Maine
89 V3500 Chevy or GMC 454W dump 135.5, parts truck, bought 454 H5D harness, engine brackets, etc. this summer, Hooksett NH
88 V30 Chevy dump, 350M, 159.5" WB, 50K cemetery truck, parted because of cracked frame. winter 2010/2011. Lebanon Maine
Yes, carb/leaded gas with factory stainless duals versus TBI/unleaded and cat. single exhaust dictated crossmember, fuel filler necks etc.