I just got a 1973 Mustang. I was told it has a 351 Cleveland and a C-4 Trans and a 9" rear. I am going to be changing the trans fluid and the rear end oil. Any suggestions on the best trans fluid and rear end oil. I use full synthetic in most of my vehicles, I noticed a huge difference when I changed to full synthetic in my 2000 F-250 rear end and manual trans.