Need size of gas tanks for 88 Chevy Crew Cab Dually

I have an 88 Chevy Crew cab with 454. Been trying to find out what the gas tank sizes are. Both need to be replaced. It is a dually and no one seems to know anything about the tanks, not even the dealership is any help.

I have filled both of mine and I have dual 16 gallon tanks. I believe there was an optional 20 gallon tank tho. Check out LMC for replacements. They are not too expensive. You can also upgrade to a Suburban gas tank. They had a 40 gallon option.

Oreilys website has size dimensions. There is 2 different sizes available.

Thank you very much noclrnce, you gave me a web site that gave me a ton of info that I was looking for including the break down of the vin. laidout84 tried your web site but could not fine it. Thank you to both of you for trying to help me out.

When I was looking for the same information they had dimensions and gallons listed. I was trying to match the gallon to decide on a fuel cell ,blazer tank,or tahoe tank.

laidout84 that is the info I found on LMC is the measurements for the 2 types of tanks which I hope will help me find right ones I need.