The Dana 50 has one of the most unfair reputations because it isn't a Dana 60 %) I personally believe if the Dana 60 didn't exist and the Dana 50 production run was longer, everyone would be building Dana 50s and talking about how much better they are than Dana 44s.
A Dana 50 has much more in common with a Dana 60 than a Dana 44; in fact most of the components on a Dana 50 share the same part numbers as a '99-'04 Dana 60, and the only part I am aware of that directly interchanges with a Dana 44 is the pinion yoke and perhaps the ring gear bolts. A Dana 50 is bigger and stronger than a Dana 44 in every way except for its pinion spline count/diameter.
The Dana 50 housing is identical to a '99-'04 Dana 60 housing with the exception of the center section casting since the hypoid offset of the gears is different and the carriers are dimensionally different. The other big disadvantage of the Dana 50 vs. the Dana 60 is that the inner axle shafts, which are the same 1.5" diameter as the Dana 60 shafts, neck down to 1.31" and 30 spline at the carrier (same as a Dana 44) instead of remaining 1.5" diameter and 35 spline. Last I looked into it, you could order a 35 spline ARB and run Dana 60 axle shafts if you wanted, but since no one builds Dana 50s, it is kind of a special order thing and not something you'll see listed. No one makes upgraded material Dana 50 shafts, so to upgrade the inners from stock, you either need to convert to 35 spline, or have custom shafts made. The outers are identical to a Dana 60, so you can just run aftermarket Dana 60 stuff.
Here is a picture to show you what I am talking about with the inner axleshafts
Basically, the Dana 50 is just as big and heavy as a Dana 60, but little weaker so every one says they are crap and just run a Dana 60, and they are right, except for cost. People practically give away Dana 50s because they are "junk" and Dana 60s are harder to find, and when you do, people want a lot more money for them. However, a stock Dana 50 is substantially stronger than a Dana 44, and even a fully upgraded Dana 44 can't quite match every aspect of the Dana 50. The Dana 50 has a bigger ring gear, Dana 60-sized U-joints, and 30 spline outers in stock form. The achilles heel of the Dana 44 has always been its joint size since that isn't really something you can upgrade on a Dana 44.
Here is a quick breakdown of the specs between a '99-'04 Dana 60, Dana 50, and Bronco Dana 44:
Ring & pinion
Dana 44: 8.5" ring gear, 1.375" shaft 26 spline pinion
Dana 50: 9" ring gear, 1.375" shaft 26 spline pinion
Dana 60: 9.75" ring gear, 1.625" shaft 29 spline pinion
Axle Shafts & U joints
Dana 44: 30 spline inner (1.31", stock shafts neck down smaller), 19 spline outer (1.175"), 1310 size U-joints
Dana 50: 30 spline inner (shaft necks down from 1.5" to 1.31" 30 spline diameter), 30 spline outer (1.31"), 1480 size U-joints
Dana 60: 35 spline inner (1.5"), 30 spline outer (1.31"), 1480 U-joints
Housing Tube Size
Dana 44: 2.75" OD .3125" wall
Dana 50: 3.5" OD .375" wall
Dana 60: 3.5" OD .375" wall
How close is it to a 44? There is a way to shave a little off the outside of the ring gear and use the D50 gears in a high pinion 44 housing.
I think what you are referring to is the
Jana 54 conversion which does not involve turning down the Dana 50 ring gear (defeats the point of the conversion). It requires the use of a 3.73 & down Dana 44 carrier and special conversion bearings to offset the carrier since the distance between the ring gear mounting flange and pinion centerline is larger for a Dana 50 than a Dana 44. You can't us the Dana 50 carrier because the carrier bearing journals are larger than a Dana 44. This conversion requires a bunch of grinding to the Dana 44 housing and non-standard conversion bearings to match the bearing journal diameters of the Dana 50 pinion to the Dana 44 housing bore. Some of the bearings are marginally weaker than stock as a result. The gear set however is significantly stronger than a Dana 44 gear set (especially a low pinion Dana 44 like the Bronco comes with).
For the OP, I don't think a Superduty axle swap makes sense on a primarily street driven Bronco, especially if you are planning on running 37" or smaller tires. However, if you do decide to swap the Sterling in, a Dana 50 is a much better choice than trying to build a Dana 44 to match. It will take a lot of money just to make a Dana 44 comparable strength-wise to a bone stock Dana 50. That said, I would only run a Dana 50 in lieu of a Dana 60 if you get it pretty much for free and aren't planing on 40" + tires and hardcore wheeling.
