Drive a 1979 ford ranger (F150) with a 302.
(Limited slip).Istead of the C4 trans i have now,should i go with the C6?

no real need to switch up to a C-6 unless you have highly modified the 302 to put out over 300+ HP, the C-4 is fine for what the stock motor can do and it is lighter than a C-6 also.