Good morning. I have a 93 GMC K3500 with the 6.5. I've had my transmission replaced twice already because of an electrical part they said was causing the transmissions to go bad. It was this second time I was told that and they replaced it with a newer part that bypasses the older one. This one shifts hard in 1st, 2nd, and 3rd, especially when it's warmed up. They told me the transmission could be adjusted but they wanted me to drive it for some time. I did and I ended up taking it back to them months later. They told me nothing could be done because it's just the kind it is..I know that's not true. I was told by another to change the input speed sensor. It didn't help. Any more ideas?