I see the part no.'s are different for saddle tanks for 73-80 and 81-87. But will they bolt up to the frame the same? My understanding is that the inlet tube is a larger diameter on the newer tanks and requires a different sized filler neck, but that's it. Any insight? I want to buy a polyethylene tank for my truck and I have an 87 bed on a 70's frame. I figured I would buy a 81-87 tank and use a newer filler neck. I would hate to buy the tank and it not bolt up. -- Mike <font color=blue> The mud's on it to hide that it's more than one color.