It is not uncommon to lose or have missing tailgate retainers on soft top TJs. Bestop has an answer with their retainer kit. The kit includes a tailgate retainer bar, retainer mounts and hardware. It will work with OE and Bestop soft tops.
Fits 1997 to 2006 TJ Wrangler, Rubicon and Unlimited
Comes with bar and mounts
Works with OE or Bestop soft tops
Includes tailgate bar, 2 retainer brackets & hook-n-loop attachment for original Trektop Classic (not NX version)