I have a 64 1/2 mustang, it needs more transmission fluid, it has either M2C33 C or D in it already, but all I can find is the type F...is it okay to mix the two? or is it best to drain it all out, and just fill it up with the type F. thanks.
Likely it has type F in it right now . Type F will work fine . Most fluids out there like Mercron would work but might cause slippy shifts (which you don't want) . Type F works perfect in C4's , no matter what year .