I got Toyo G 8x10, but the GG is missing so I have a few questions about the GG..

The one important thing to know whether the orinal back did have fresnel or not. If not, then it's quite easy to find some GG.
The advise about good GG's would be nice The cheapest ones on eBay are from hong kong, but I don't know how good they are.

If the original will have fresnel, then I need to shim new GG - if I am correct?