What is the plastic plug in the bottom of my 97 F150's transmission? Previous posts indicated it is something from the factory, but they did not specify if it is required. Can that plug be left out?

 

yeah i think it plugs the hole for the dipstick tube before they install the trannys don't worry about it.....

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pacific green 97 f150 4.6l..reg cab flareside 150XLT ,ROUSH suspention down 3 fr and3.5rear with BILSTIEN shocks,3.55LS,snug lid,carpeted bed, painted tailight accents,4x4 grill &bumper,k&n,SUPERCHIP(THANX MIKE),poweraid,ram air kit,valvoline synthetic,accel super stock wires,platinum plus4 plugs,flow master muff,blue halogen bulbs, speed-glo dash,carbon fiber gauge accent,..."#6 sticker!!!!"
STEREO:eclipse head unit ,boston seperates ,orion amp, pioneer amp,2-orion 12's,custom box by me!,sony adjustable crossover,1 farad cap&way to many cd's

 

The yellow LoLLY PoP your refering to is installed on the assembly line to prevent the fluid from leaking out when the trans is installed. When they insert the dipstick tube in place it pushes the LoLLy PoP into the trans where it falls to the bottom of the pan.

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2000 F-150 Lariat, Flareside, Black, SC, FOxFO, 5.4L, 3.55, Garmin Street Pilot Color GPS

 

Unless he's talking about the Outside of the trans, in that case it could be the black cover plug to reach the Torque Converter drain plug. If that's the case, put it back on when done.