Transmission Component Slipping

[CarlosH1]

Hello,

I get a hard shift into second gear, like it jolts into 2nd but not all the time. I only notice it after driving on the freeway for several miles. It has 60,000 original miles. Service Engine Soon light come on after the hard shifts with a transmission fault code. I reset the Engine light and let it set 20 or so minutes and it shifts like new. I changed the Transmission fluid and filter but the problem is still there.
Any help would be most appreciated

Thank you

1997 CHEVROLET TRUCK S10 2WD
6 Cylinders 262 X 4.3L SFI