Heatsink (W567F)
The heatsink arrived in a box labeled with a sticker marked with the Dell part number: W567F.
Memory shroud and fan (P787F)
This part arrived in a box with a more detailed label: "P787F. Internal part: GFF8K"
I specifically ordered part P787F, however GFF8K appears to be an alternative part number. In fact, the label on the box was covering another label that looked like the labels on the other boxes. This hidden label read: GFF8K. So, there could be two part numbers for this specific part.
Research also revealed that the fan on the memory shroud may be available as part Y730D. I did not order this part as it was included in part P787F.
Dell Heatsink Assembly
Some research reveal that the heatsink and memory shroud may be available as a single part U414F. I didn't order this part specifically, so I couldn't say for certain that it is the heatsink and memory shroud, but a bit of searching seems to suggest it is.
These pictures are the heatsink and memory shroud attached together:
Riser card (H236F)
The hardest part to find is the actual riser assembly. The part I ordered was H236F. It contined the circuit board and a metal bracket.
Details of card
Here are two links to the T7500 service manual on Dell's website. Although they do not include part numbers, they do include installation details of the second CPU riser and assembly