planning on buying a 96 Silverado, trying to swap something in with a t56. looked at the L76 and seen they have dod and vvt, do those have to be deleted or can they be kept and save gas? looked several others such as ls1, lq9, l33. will all these bolt up to a t56? trying to get the best bang for the buck. if it save gas it would be good, heard some swaps get 20mpg highway (I know v8 and gas don't mix but some are betters than others).