I have a 1993 GMC Sierra K2500 with the 6.5 Turbo Diesel, It has a 5 speed manual transmission - And I am wondering what one it has, or how I can tell which one it has. My current one has 301k+ on it and it is starting to fail (popping out of 1st gear, 3rd gear is making a popping noise, whining) I've checked my fluid level and it's fine, Changed it, No change.