How do you glue these back on?

The cost of $750 for repop plastic surrounds was the big reason for doing this. I bought a header panel with broken grilles bolted in it along with a cache of 69 cuda parts for my sons car. The broken grilles stayed in the header because i wasnt sure how i was going to fix them, and the fact that i wasnt going to just remove some good parts off them and pitch em. The whole pack rat mentality i guess lol. The biggie was the $750 though.

I figured i got more time than money. Couldent hurt em any worse than they are. Honestly though, if the new ones were $150-$200 for the pair, i wouldent have bothered fixing these. 50 year old plastic is brittle as hell. I dropped one of em, had to glue it back together all over again in different places. These pieces are fine once assembled and bolted in the header, but until then need to be treated with care.