I noticed on my newly acquired '70 K5 that it had the standard mechanical fuel pump next to the engine as well as an inline electric pump next to the filter attached to the frame under the RR fender well. With the standard 350 V-8 and 4bbl Holley I wouldn't think 2 pumps were necessary. Is this someone's backyard project or factory? Any advantages/disadvantages to this? Also, the manual says this engine came with 2 different Holley carbs -- the 4150 and 4160. I can't find any ID tag. Any physical distinction?