Bert yoke length?

What is the max yoke length for a non ball spline tail?
I have a new setup and the 8 inch yoke only goes in 5.125 inches. Is this normal?
I dont want to take the tail apart if I dont have to.
Thanks.

yes the normal bert is splined for a 6 inch yoke to use the 8'' yoke you'll need to have the tailshaft undercut just past the splines.I do this modification at my machine shop for the local racers. in the photo you can see a standard tailshaft and the modified shaft.

Thanks, I need the tranny now, but Ill get the mods from you this winter.