So IIRC the earliest cars used plastic fuel tunnel lines from front to back, but were replaced at some point with lines that the forward-most ends had a formed steel barbed section that poked through the grommet.
Those lines were asymmetrical sized. The pressure side smaller than the return so on the early version of the grommet the hole sizes matched the lines.
It had only 2 holes for the lines since the charcoal evap system & cannister was in the cowl with 2 large vinyl lines running along the drvrs side long & into the the eng bay.
That was changed on the later cars where the charcoal can was moved to the Eng. bay & the 2 vinyl lines were replaced with a single small (4mm) line that also poked through that grommet & now ran down the tunnel into the eng bay.
That change coincided with moving the pump to the front so the lines changed material & became symmetrically sized as did the holes in the grommet.
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