4 speed drive shaft

The 727 splines are completely different from the 904s.
The 833 has two yoke sizes. The standard one which is the same as the 727, and the smaller one. The smaller one came in the LD,O/D boxes, and is the same as the 904 ones.Just to confuse you, the O/D boxes also came with the larger 727 yoke. I have a couple of those.
If the 904 yoke fits the 833 then use it. you may have an F-body O/D trans with the small output shaft. Point is; use what ever yoke fits the trans, and same at the back. The actual tube length is the same or very near to the same.
There are three rear yokes available; the 7260(small), the 7290(med), and the 1350(lge).If you are going from a 904/7260 to a large yoke 833/1350, then the D/S may be a little long. Which would be the perfect time to move your rear axle back, to fit it all in.And you would require a special U-joint to adapt the 1350 to your driveshaft.
The 1350s IIRC were never offered from the factory.
If you have more than 400hp,stock springs(major wind-up), and slicks you should consider 1350s. If more than 450hp, stock springs,consider them mandatory. With traction devices, I might consider them a little later.They tend to keep the pinion angle more stable.
For street use, and a healthy V8-M/T,consider the 7290s mandatory. Ill tell ya, picking up your driveshaft off the highway the first time is just embarrassing.The second time is majorly aggravating. The third time; well I didnt let it go that far. Anybody that tells you to put a small joint in there to act as a weak link, Kick him in the.......Well just kick him.
If you want a "weak link", get a clutch with flyweights in it.Find out where its calibrated, and try and stay below that rpm in day to day driving.Or get a stock 340 disc, as opposed to the CFII. The CFII disc is hard on parts thats for sure. The 340 disc doesnt last as long but is very street friendly. Oh yeah, it wont last long for track duty at 400plus hp.Even on just DRs.But the street friendly manners of the 340disc,in a DD, are more than worth it. And the CF diaphragm clutch is sweet.