Drive Shaft Spacer

[drewr]

Does it make sense that I need a drive shaft spacer? I was trying to mate up my SBF 347/TKX with my Mustang rear end. The nut on the rear end flange is too tall to fit in the divit in the drive shaft. I’m almost at the max end of the slip yoke in any case. A space would fix this, I just want to be sure I didn’t make a mistake or have a wrong part. This a Type 65 complete kit.

See pics. I appreciate the help.

169547169548

[drewr]

Of course the manual has no mention this. I thought I had a pretty old school vanilla set up.