Noise when shifting into drive

[massivespl]

when I go to shift into drive I hear a metal slapping Metal sound. It sounds like it’s coming from inside the tranny and not the u-joints... it shifts and runs fine just when u put it in drive it makes a pretty loud noise. Anyone have an idea what it could be? I’m gunna take it to a tranny shop Monday. I already went to one shop and they said drive it until it breaks. Lol but I’d rather not be stranded somewhere and get it fixed.
2011 ppv with 6speed

 

[Doubeleive]

slip yoke most likely, my trucks both nbs and nnbs have done it, my nbs was more prominent putting it into gear pretty much anytime, and the nnbs is more prominent when parked on a small incline and I can feel it anytime I step on the pedal apparently I have a heavy foot