I like some others think that the AUTOMETER gages are a very good choice. I am not for putting mechanical fuel gages inside of trucks, I just don't think fuel belongs in the cab. The ones that use an isolator, or electrical sender are fine. I have a PRIM-LOC and I installed two mech gages, one pre and one post filter. They are both located under the hood, which isn't as convenient as in the cab, but I think wiser. They are great for letting me know when to change my fuel filter, just look for the pressure differential. It seems you can't just go by a set time, or mileage, I have had to replace them with as little as 1500 miles on the new one. There seems to be alot of places that have very dirty tanks, and apparently they do not use a filter.