Identifying Eagle Transfer Cases
about ID of cases without the build tags (a 2" round tag with a screw in the middle of it and lettering stamped in it) -
The 119 case will have no linkage attachment where the shift fork comes out of the front half of the case, it will only have a locking nut to hold the non-moveable shift fork in place, or it is a bolt plug, if there is no shift fork(haven't had a 119 apart, haven't looked at an exploded diagram to see if theres a shift fork er not).
The 128 and 129 will look the same from the outside. Both will have a shift-able linkage attachment. On the 128, you will be able to relatively easily turn the front and rear outputs against each other(turn each the opposite direction of the other) when it is in 4wd mode, since it has an open differential. I'm not sure if its a lock-able differential like the NP 242, where the differential is locked when the case is in 4wd Low mode. Its probably not lockable. Anyway, the 129 has the viscous coupler, and it should take some considerable effort or even a wrench to turn the front and rear outputs against each other when the transfer case is in 4wd mode.
So 119, no shifter linkage attachment
128, has shifter linkage attachment, open diff, can turn outputs against each other in 4wd
129, has shifter linkage attachment, viscous coupler, difficult to turn outputs against each other in 4wd
Even a worn out viscous coupler will have much more resistance than the open diff.
Thanks to txjeeptx for the info