steering box interchange

[YELL78]

i have a 78 1/2 ton SWB that the steering box is starting to leak quite a bit my question is, is the steering shaft connection the same on the 78 as it is on like an 80's model

 

[87GMC]

I'm pretty sure the shaft size is the same, but the lines may be different. Earlier years used a flare fitting. Later they went to an o-ring fitting.