Best I can tell the reg cabs below SR5 trim are "base" models. Base models with V8's are called DLX's. The only upgrade is the engine(s) and equipment included with whichever chosen V8; tow pkg or not, brochure states trans temp guage is standard with 4.7 if it is equipped with tow or not, 5.7 deletes guage when tow is deleted. There are no soft trim differences between V6 and V8 base/DLX models, and exterior differences are just additional emblems. The base/DLX seat is very similar to the fabric used in base Tacoma's, and upgraded sport seats in TRD Tacoma's. The pattern is slightly different but the fabric feel and weave is the same. So, if you have seen a base model with a V6, this is the fabric You will get. The SR5 seat fabric is more of velour type. SR5 interior is included with Sport appearance pkg and TRD, with either buckets or bench.