Evaporator Core Differences

[Rugby_7]

In my research looking for parts form my 1975 k5 with a 5.3 I found that the evaporator cores changed in 1977. The only difference (besides price) I can find is in the orifice tube. the 75 has some sort of an adapter and orifice tube while the 77 has just a orifice tube. They both use the same accumulator. Any reason I shouldn't go with the 77? Would it be easier adapting the 77 evaporator to r134a?
1975
http://www.rockauto.com/en/moreinfo.php?pk=814346&cc=1029451&jsn=617&jsn=617
http://www.rockauto.com/en/moreinfo.php?pk=815425&cc=1029451&jsn=619&jsn=619

1977
http://www.rockauto.com/en/moreinfo.php?pk=814346&cc=1029451&jsn=617&jsn=617&jsn=617
http://www.rockauto.com/en/moreinfo.php?pk=815425&cc=1029451&jsn=619&jsn=619&jsn=619

 

[6872xtc]

I didn't look to see if that '77 is the same as the newer stuff, but I can tell you that my '90 has been running R134 for several years. It was converted before I got it 4+ years ago. I don't know what orifice tube it has, nor do I know what my buddy has in his. Both work well around here.

 

[Rugby_7]

I didn't look to see if that '77 is the same as the newer stuff, but I can tell you that my '90 has been running R134 for several years. It was converted before I got it 4+ years ago. I don't know what orifice tube it has, nor do I know what my buddy has in his. Both work well around here.

I ended up trying my luck and ordering the 77 one. It was $30 cheaper than the 75