One what?
Oh, right, the number!!!
The number 7 was the 'Americanized' version.
Looking at yours, it seems to be a bit of a hybrid.
The 7 had the link and pin couplers.
It had a black frame, not red.
It had a bell and a bigger headlight.
and the cab roof was different.
I think that's about it.
Maybe there were some that were in between.
I assume that it was the US Aster importer at the time who organised the number 7 as they were selling both types.
All the best,
David Leech, Delta, Canada