Some model D44's use different diameter ,and thickness, tubes but most folks don't ever get into wanting one for the other. I just thought I would mention it just incase you ran into this problem gathering u-bolts or steerring stabilizer brackets. Your 1974 housing "should" be the smaller tube but thicker than later model housing that used a larger diameter tube but a much thinner one.
As for the Spicer hubs - the pre 1976-7 big hub Spicers are great hubs but they are no stronger than the internal style that replaced them. Infact most folks have a problem with an external style hub mount by the retaining bolts loosing torque after usage and time ( Loctite is the best method to avoid this common problem ). The internal Spicer hubs that replaced the external units are every bit as strong and are more user friendly; ( although they do not look as stout) the internals are considered the stoutest style hubs made - Spicer hubs that is .
Tom