I sold my CA18 + H165 + sedan tailshaft to a mate with a CA18 + H165 + Ute. And worked fine.

This tells me that the Sedan and Utes, share the same distance from gearbox to centre of rear wheels. The difference is only in the 'nose length' of the diff unit.

I do believe that a Ute tailshaft will fit into a sedan with a H165 fitted.
Some quick measurements at the next Datsun Cruise would tell you for sure.

Remember that the manual and auto gearbox tailshafts are different lengths.