weird shifting
 

Hello all,
So new guy here. Been lurking on this site for awhile reading. So here goes my problem. I recntly got a 2001 f250 7.3 I love it, been waiting years to get one. ive had it for about a month and have noticed that the truck seems to not shift into 4 gear. I can get it up to around 45-50 and it feels like it never shifts to another gear I get the rpms to around 2500. I can get it past that but iam afraid to push cause I dont want something to break unto I know what it is. When I let off the acceleration the rpms drop and almost feels like Iam in another gear.
The od button doesnt work on it I need to replace the whole shifter column cause its so lose so I figured id replace it all at once.
So is this normal lol? Is it going from 1-2-3- to od ? Or am I missing it shift intp 4th?
I know this seems hard tp understand so I want to make a video of it to show you guys What I mean.
Thanks in advance