6500 and 6510 nameplates are both rare...but are different. I think 5500 will work for 6500. 5510 and r600 can be used in place of 6510. All of these nameplates (and hoods) are hard to find, and typically expensive when you do.
Here's a set of 6510's; they'll go for a lot (over $50 already):
http://www.ebay.com/itm/Shimano-Ulte...item3390b3f816
http://www.ebay.com/itm/Shimano-Ulte...item3390b3feb9
__________________
"The older you do get, the more rules they're gonna try to get you to follow. You just gotta keep livin', man, L-I-V-I-N." - Wooderson
'14 carbon Synapse - '12 CAAD 10 5 - '99 Gary Fisher Big Sur