Check out these:
GrannyDollars.com
All CCBill
GRANNY LOVES BOYS:
BIG TITS GRANNIES:
FAT GRANNY SLUTS:
Here are a couple of sample FHGs, all have large thumbnails, thumbnails are also in a large number of precut sizes:
BIGTITSGRANNIES FHG SAMPLE
FATGRANNYSLUTS FHG SAMPLE
GRANNYLOVESBOYS FHG SAMPLE
Check it out:
GrannyDollars.com