Automotive Plastics: Cracked screw post, tail light broken post, gussets

Question
Have had difficulty replacing damaged right rear tail light of 94 Buick LeSabre Ltd. After several attempts to locate/replace tail light assembly by visiting salvage yards, had to settle for a 92 year assembly (and physically it fits) but after checking closer  and starting to screw in the assembly I realized the plastic is cracked on one of the three screw posts. The posts have rubber covers but can be lifted to make adhesive application when I figure out what to use. ( I do apologize for the lengthy mail) I have read the various messages on this site and cannot pin down what adhesive to try for I cannot find identification for the type of plastic the posts are made of. The assembly inners have several marking but none that would id the plastics I would think. Should I be looking for the codes the plastics governing committe (forgot the name) put out several years ago. Do you having any suggestion either to id the plastics or the best adhesive to try in this situation? You advice would be appreciated.

Answer
Hi Lisa, the best way to repair a broken post whether severed from the very base or in a low place near of it, is by inserting small pieces of perforated metal similar to those that you may easily obtain from a discarded grille of a car loudspeaker or any other but smaller like the one we may see in the door of a regular microwave oven. To reunite the two parts you can make use of a soldering iron to push in the metal in the cracked area so that the plastic flows through the holes. once cold, this is a very strong union that you may improve by applying some hot melt glue on top.
if the work was done properly, that post can stand the whole weigth of the unit by itself.
that is the way to fix any plastic if we ignore the plastics id. good luck if you will give it a try...