try NAPA or any parts store.
I'm sure you could if you can find the parts you need and have the experience to do it.
Any good parts store should be able to get the push rods for you and if they can't try Manciniracing.com.
you can try manciniracing.com.
In a chiltons repair manual for 72 dodges.
look on the internet as their are companies that will custom make weatherstrip for you.
If you can even find them they are big money.
go to manheimgold.com and figure out the price.
You can try to find 1990 Dodge parts online. There are many auto parts manufacturers online selling their parts.
go to the library and get a chiltons repair manual for your car.
Dodge/Chrysler dealerships, specialty auto parts stores.
Call your local Dodge Parts Department.