Yes from everything I read seems like the Synco Goes out in these transmissions frequently. I purchase mine change the fluid and within about two months my second gear started going out. Tried to find rebuild kits and also quotes from transmission shop. I couldn’t find a shop within 2 hours of me that would work on it. I found out that the parts kits are junk. I called some shops on line and they all stated that the AX-15 was the way to go. Start doing a lot of research and found that this is a very very common issue. So All the research I did showed that everyone was going back to AX-15. Seems to be a tried and true transmission. And if you look the the NV 3550 was only put in the Jeep for four years and then they got rid of it.