Drive Shaft Questions

[mudrunner88]

I'm a little confused the past few days about drive shaft lengths.

I noticed so far there is 3 different lengths. My '85 4Runner has a short rear drive shaft and the diameter of the tube is small.

A few years back I took apart a truck equipped with a G52 4wd...I tried to install that drive shaft and it was too long.

My buddy Al had another behind his shop from a V6 extra cab and that one was even longer?

Then we looked at his 4wd 22r and it has the medium length one (same as the g52 length) but it's double cardon-jointed???

So my question is: Does anybody have a write-up on drive shaft lengths, years, and models, wheel bases etc.

2nd: What was the purpose of the double-cardon joint if I can get the same drive shaft length solid from a different truck?