Dana 44 Axle and u-joint help

[BrianG]

I posted a similar post in the 67-72 pages, but realized this might be a better place for answers to this question.

After hours of searching, I can't seem to find an answer to a couple of questions.

I have two Dana44 Axle assemblies. I'm trying to make one. The one that is under the truck which I am rebuilding is a smaller tube (older I believe) unit. I just replaced the ball joints and am half way through with the axle u-joints. I needed some parts off the other housing that I have so I tore it apart. Upon doing so, I realized that the axle shafts are much thicker in diameter on the one that is not under the truck. I also realized that the one out of the truck has bigger axle tubes. I believe the one that is out of the truck is around 76 or 77 and the one under the truck is possibly a 72. I am planning on using the hubs and spindles from the newer unit. (more confusion here, because it seems as though there was a changeover of parts at this time and you could have one of two bearing sizes)

So, my first question is, can I, or should I use the heavier axles from the big tube Dana 44 in my small tube Dana 44 housing??? The lengths seem the same, the splines all match up, only the thickness seems different.

My second question pertains to the u-joints. I've read and read about differences in the u-joints, but I have installed one already and it seemed to go in with no issue, so I think I'm good there. Can anyone tell me if the u-joints are just really close and maybe it just seemed okay when I put the one in, or are they enough different that I would have been able to notice? Like I said, it seemed to go in just right, the internal snap rings lined up correctly and the joints seems to operate properly.

Any and all help would be greatly appreciated.