The pre-'74 factory 4X4 had a similar short shaft, not sure how the length compares to yours.
74 was the last year for the divorced part time transfer case as far as I know. This is a 74 that had a 13" shaft with a NP 435 and NP 205 transfer case. The 2WD NV 4500 is 8" longer than the NP 435, not sure about the automatic trucks, but I know they used the short output shaft 727 with a fixed yoke.