new fuel pump

during a recent installation of a new fuel pump my mechanic friend forgot to install the rubber sleave around the new fuel pump before installing it in the fuel tank of 1994 bravada. When i realized this and brought it to his attention he says it is not a big deal don't worry about it. Any opinions?

Are you referring to the rubber seal at the fuel tank/fuel pump flange?

the rubber boot wraps around the fuel pump as a sort of insulator.
Thanks

The '92 Service Manual describes the rubber boot as a sound insulator with no other purpose...if you can endure any extra noise, it looks ok.