I have a 94 Suburban. I have to go look at my truck later today but I should have a TCM390 in it. I was told this one uses the Injection pump to shift, I am downgrading my truck from the 5521 pump to the 4911 due to it being simpler and easy, plus I can run black diesel on a 4911. The trucks old than 94 use a TCM609. My questions is does the TCM609 just run off the trans to shift and if so can I just swap it out with my TCM390? or do I also need a new wiring harness?