Dana 300 rear HD Output Shaft. This is the Advance Adapter 50-3034 for '80-'81 short style Dana 300. Comes with your choice of 1310 CV or 1350 CV yokes. Used 1 season then got the chance to upgrade to a different t-case. $300.00
To say it won't work isn't quite true. This kit will bolt-on to 1980 cases only, but the later cases can be modified to make this work. Jason is correct about the bolt pattern being different - 1 of the 5 bolts won't line up, and it requires mods to the transfer case to accommodate the one bolt. Luckily though, the AA kit for the early 300 uses the late style speedometer gear and housing, so no mods would be required in that department.