What Do You Do
 

I Have 1990 300e, The Turn Signal Covers Are Both Cracked And Dirty, I Have Noticed This Is Common On These Cars. Any Ideas Or Upgrades .

Upgrage to Euro-spec lighting rather than invest any money on OEM (USA)
Use "search function" to find how much better they are. The corners could be cheap to replace by comparison with the upgrade if you have a budget.

Replace them with OEM Bosch lenses from a 94 - 95 E320. They will fit perfectly, will be clear and thus 'euro', look better and fit better than the aftermarket ones that I've seen, plus have the required DOT yellow reflector on the side (check the Code of Federal Regulations, its in there) and thus are 50 state legal.