drive shaft freeplay lenght fit

OK I have a new drive shaft kit I purchased years ago with the larger u-joint support. I need to take the shaft to the machine shop for it to be cut to size and balanced.

My question is this. When I pulled out the old drive shaft after taking the straps off the diff. when you push it up into the tranny, mine I know is to tight. I can barely get the ujoint to clear the diff yoke. So how much clearance should I see when the drive shaft is pushed fully into the trans from the diff view?

My feeling now is that I can get the drive shaft out without prying but I think it needs at least another 1/2-3/4 s of an inch for travel?

What should it be?

thanks.