Two days ago while driving through the city my transmission started missing gears. It would rev up to about 3-4k then shift really hard, even at slow cruising speeds (e.g. 25mpg @ 3k). I stopped and checked the fluid level since I had this problem previously when a belt snapped and snagged a big hole in my transmission cooler lines. So I got some more transmisison fluid (ATF-4) and topped it off. The next day it acted up one time on my way to work but today on my way home it was doing it even worse than the first day. I stopped and checked the fluid, it was full. I'm at a loss guys, is my tranny going out?

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1963 Ford F100 - Cummins Swap?
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