Hello everyone, just created this account. I have an issue I cannot figure out yet. I have a 2000 mustang gt. Last October I replaced the trans with a used one with 40k miles on it from a 98 gt, also replaced the clutch. This morning, after getting my CDL, I was driving on an on-ramp here in Ohio (idiots cant merge here), and attempted to shift from 4th to 5th gears and 5th kept kicking out. I tried this several times an didnt work. SO I drove in 4th around 65 mph, 3k rpms for several miles. During that time I would try to get in 5th again with no success. I had no issues prior to this besides the usual reverse hard to get. The final time I tried to grab 5th, the shifter froze and I couldn't get into any gear. It was as if the shifter was froze. I had to use both hands and pull it into neutral, clutch engaged and coast over 4 lanes of highway traffic to the side of the freeway. I waited a bit, maybe the trans got overheated or something to that effect and the shifter still would not budge unless I used both hands and all my strength to push and pull into each gear, 5th was unsuccessful still. The clutch is fine, I checked the quadrant under the dash by the pedals already. It does still have the stock clutch cable with the plastic piece under the hood it mounts to the firewall ( non-adjusting). Shop said a good tranny flush may help and thats $130 at the local Valvoline quickstop, May do that before taking it to a shop . Any advice and thoughts are appreciated.