17mm spanner alternative for fuel pump?

[DT1]

On the main fuel pump the banjo union to the accumulator is secured by a 19mm nut to the outside with a 17mm nut on the inside.

Unfortunately there is not enough room for a 17mm spanner because some idiot put the posts for the terminals too close to the union (who the hell thought this was a good design?).

Is there a tool designed to hold the 17mm nut in place so that I can exert some pressure on the 19mm nut?

I've done it using a pair of mole grips but I'd really like to know if there is a special tool for this.

Thanks.

[Nate]

get a good fit 17mm spanner and attack it with a grinder to make the sides thinner. a decent quality one will be more likely to keep its shape after being made to fit, as it will weaken them

[DT1]

I had been looking at fabrication.

It's just such a bad design.