It was my understanding that fingering on all pennywhistles is the same; it dosent change from brand to brand or key to key. Regardless of brand or key, “D” is fingered with all 6 fingers down. I noticed that one of the vendors says that the Susato comes with a fingering chart. Pictures of these charts are not very clear, but they appear to have different fingering from the Clarke, (as an example). Is this true, or am I misreading the charts pictured?
Thank you for your time and attention.
Hi joemich, welcome.
Yes, that’s basically right. You’ll find some minor variations - C-natural, vented D, 3rd octave notes. Otherwise the basic diatonic fingerings are universal.
You’re probably looking at Thom Larson’s page here:
http://www.thewhistleshop.com/catalog/whistles/inexpensive/susato/dublin/dublin.htm
The upper chart are the bog-standard diatonic fingerings.
The lower chart are the chromatic fingerings (sharps and flats) - where preference is given to cross-fingerings instead of half-holing whenever possible. Those cross-fingerings are also fairly standard and will work on many whistles besides Susatos - including Clarkes. But there are usually several fingering options for a particular note on a particular whistle, besides what is shown on the Susato chart, and it’s worth experimenting to find the ones that work best. This is part of what any good whistle player does in preparing to play a given whistle.
The Clarke chart, on the other hand, gives only half-hole fingerings for the chromatic notes. That’s the difference that you see. Of course, half-hole fingerings can be used on any whistle as well.
So put the two charts together, and you have the (more) complete picture.
The Susato Chart that I have is different from the link.
It only gave the Diatonic Scale. 
I can’t put my fingers on a Clarke chart at the moment.
Susato have a pdf of their chart on their website which should be clear enough - http://www.susato.com/konakart/downloads/Pennywhistle-Fingering.pdf
The Susato chart recognizes that you can be a bit lazy with some fingers on the high notes.
Thom Larsen has a chart which only shows the first octave and assumes the same fingerings for the second. http://www.thewhistleshop.com/misc/fingering.htm
But, as MTGuru said, it’s all basically the same system from whistle to whistle. All whistles are not created equal so sometimes you may have to experiment to see what works on a particular whistle. The optional fingerings may facilitate going between notes with less movement than the standard fingerings or provide shortcuts. Playing notes as harmonics is possible too. But the basic diatonic major scale and fingering should always still work.
Here’s a great chart if you want to examine the depths.
Hope that doesn’t just add to any confusion you may have.
Feadoggie
You’re right, Angel. My Susato chart is only diatonic, too, like yours. It’s basically the same as the one that Feadoggie linked to, but with slightly different text at the end. My chart must be 10 years old now, so the one on the Whistle Shop page must be older than that. Too bad it’s not really legible.
Thank you very much for the detailed responses! Now I’ll go off by myself into a corner and really absorb all I have been given. Thank you.
Joe.
Now I haven’t known that it can reach third octave.
The breath is soooooooo hard 
unless you have a quiet whistle or a whistle that requires less air.
Bb? Where do you use Bb on a D whistle?
Its not on D major, A major or even G major scale… 
You’ll find that a lot of music defies “the rules” as you might envision them.
That is a great chart. I often use that 000XXX fingering of C# around pedals with D, but I couldn’t help feeling like I was cheating and thinking that my old whistle teacher would have given out hell to me.