No 2nd gear

Ok, so I took the dart out today with my son who is home for Christmas...we did a few burnouts and a couple passes...that being said.. now I have no second gear...automatic 3 speed 904.... if you put it in drive and let it shift itself it hangs up in 1st gear and then goes to drive...if you manually shift, 1st is fine, put in 2nd is just like neutral...drive is fine.. reverse is fine... I am correct in presuming the issue is not linkage and more likely internal tranny???? thanks in advance for your advice & Merry Christmas!!!