In article ,
"Eric Schaefer" wrote:

What's the difference? I don't see any. My Unitrade catalog is no help.

Hi Eric

Typical Unitrade bad typesetting, page design and proofreading problem.

See Scott Catalogue. The J7 was issued in 1949, perf 11 and watermarked
#2 in Uitrade, #224 in Scott, whereas the J6, issued in 1939 is perf
10-10.5 and unwatermarked.

Hope this help.

Richard