Vehicle title transfer from deceased parent

This is going to be a confusing story and im a first time poster so bare with me. My dad died almost 2 years ago. him and my drug addicted grandfather shared ownership of a 1958 Chevy Biscayne. Both of their names are on the title although my dad has had the car in his possession over the past 12 years and no one has heard from my grandfather since. (we live in california , he lives in Washington) I am not sure how to go about getting the car in my name. i cant find the current title anywhere. my dad was never good with keeping paperwork organized. i have his death certificate but im worried that if i go to the dmv to try and get it transferred they will tell me they cant because my grandfather is also on the title. Im also worried they will find a way to contact him because i know he would just sell the car for drugs even though it has been in my family for years. how do i go about getting his name completely off the title and only getting it in mine? because the car has been sitting for the past few years can i claim it as abandoned? i dont know what to do and i feel like i already waited too long. my dad always wanted the car to go to me when he passed but i thought id have more time. im only 21. this is just all so confusing and new to me. if this confused anyone, im sorry. feel free to ask more questions for clarification. i will try and explain everything the best i can if i havnt already. thank you in advance.