JUst put my I6 back in got her fired up (sound great ) but going for a test drive before smog and it will not go over 40 miles an hour almost feels like there is no 4th gear engagIng will just continue to climb rpms. Changed fluid and filter And even drained it again after a few miles around neighborhood still no luck. I know my transfer case linkage had popped out when installing new engine so I jimmy rigged it on there until my linkage rebuild kit comes but it doesn't feel loose or anything. Everything electronic was working fine before engine rebuild but the car sat for a few years before it started so I'm thinking linkage adjust or something mechanical But open to all ideas thanks. Jeeps no fun if you can't open her up !