Door Threshold question

jakeclev

I have a walk-in exterior door in my garage that needs a new threshold on the cement floor. I think I've found the threshold I might need, but it's only for a 2x4 wall and I need one for a 2x6 wall. So I'm curious if I can find a threshold for a 2x6 wall or an extension for the 2x4 threshold. Where can I find a threshold with these specifications and how might I install said threshold:

-2x6 wall
-30 inch door
-adjustable threshold
-1 3/8"-1 5/8" from floor to bottom of door

Thanks for any help in advance! This is a little urgent because there is currently no threshold there and water is coming into my garage!

joecaption

No picture, no picture of the on you think might work, no mention of what the door is made of.
What happened to the old threshold?