Gasoline is listed as "flammable" and diesel is listed as only "combustible". There is no application for an auxiliary gas tank, (like in the bed) for a gas anything. You can add a bigger integrated tank though. Been there and done all that.
There is some advantage, but not much, to just new door speakers. Check around and see what you like. Without a new amp and other components, it'll just be a start.
I don't know why, but congratulations on buying a hybrid truck! I'm sure that's the future for cars in America.
http://media.gmc.com/media/us/en/gmc/news.detail.html/content/Pages/news/us/en/2016/feb/0225-sierra-eAssist.html
I had a 2015 F150 Lariat until a month ago. I am surprised to see that I am the first one to say that I really liked the floor shifter. It was a very comfortable place to rest my hand while underway. Intelligent entry and keyless ignition were great, for me, too.
The F150 had plenty of console storage for me, and I'm a contractor who drives from jobsite to jobsite all day.
The shifting is really electronic now, even though the shifter feels connected. Since in flat-tow mode the park position is disabled, it may be related to that. It's a dealer issue no matter what .
I have had just a couple of 80's GM cars (out of 80+ classics)...an 84 Riv Convertible and an 86 GN. Horrible build quality...doors all rattle, thin sheet metal (w/o the engineering they have today to make them tight) . Disgraceful cars. The GN will run though...that's for sure.
It wasn't smog so much as it was gas mileage. The 73-77 cars sold in numbers that will never be seen again, since everybody bought American cars til later. The across -the- board redesigns in 1978 were just downright ugly, plus nobody wanted a downsized car anyway. Can you imagine "upgrading" from this:
to this?:
From 73-77 those Colonnade cars were the kings of the road. Very nice car you have there. Does it have the awesome buckets/console/4 spoke steering wheel? I see you say buckets so I guess so.
Unless you spend a mint changing your rear gears, you will have very little power. And if you do, you will get 8 mpg city.
Seriously, not trying to be an ass, but if you want to do that buy another truck. You will be better off in several ways.