Do you have to drop the fuel tank replace sending unit on 69 pont. gto and where is located?

On a 1969 Pontiac GTO, you generally do not have to drop the fuel tank to replace the fuel level sending unit. However, it's significantly easier, and often necessary, depending on your access and comfort level.

The fuel tank is located in the rear of the vehicle, under the trunk floor. The sending unit is inside the fuel tank.

While some people with exceptional dexterity and the right tools *might* be able to access and replace the sending unit without dropping the tank by working through the access hole in the top of the tank (this involves carefully removing the filler neck, possibly some surrounding sheetmetal, and working blindly through a small opening), this is considerably more challenging and risks damaging the tank or surrounding parts. It's prone to frustration and accidental damage.

Therefore, the generally recommended and far easier approach is to drop the fuel tank. This gives you ample space to work safely and efficiently. It does involve extra steps (disconnecting fuel lines, electrical connections, and support straps) but drastically reduces the chance of damage and frustration. This is usually the approach mechanics would take.