As I was driving I heard a noise as it went into overdrive then it seemed to kind of drag and not go over 45 or 50 I turned the O/D off and it seemed fine. When I got home I found It also has no reverse. The fluid looks and smells fine. Whats wrong? Is it something I may be able to fix through the pan or would the whole tranny have to come out?

 

I had a similar issue on my 98 pathfinder SE. I was driving along on the highway and I hearda big bang, and the car seemed to be stuck in 4th gear.When I pulled into the driveway, I realized I also lost reverse. Once it was towed to have it lookedat, I found out it wasthe Transmission that blew.It had to be rebuilt. Hopefully its not the case for you as thats a$1700-2200+ job, but symptoms sounded very similar. Good Luck!