No there is not a top motor mount. I believed that was used on the 86 and 87 T3. The T4 used the same head as the 86 and 87 T3. Yes you can replace the sleeve and oring without splitting case. The sleeves are not available but the orings are. I had the same leak and the only way I got it to stop was to put two rings behind that sleeve. I have 3 different motors and all of them have some slop between the gear and shaft. I dont know what yours is like butI believe some slop is normal. somebody may have a better answer for this.