The only thing that comes to mind are those plastic anchors that are sold to insert in drilled holes in concrete to accommodate screws. They don't usually do a great job in concrete but they might be fine to hold the license bracket in place.

You might need to file or sand them down before cutting to the correct length and tapping into place.
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Any twenty minute job is just a broken bolt away from a three day ordeal

Yes, simply a square plastic nylon expander plug. Available at dealers, likely also in good auto parts stores in the odds and sods blister pack plastic fastener area. Household screw expanders for drywall may not expand close enough to the surface, are round so won't grip as well, also soft poly so can easily tear and may not last. Masonry expanders may be slightly better, but I would only use those if I was being lazy.


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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now