Glad i found this forum thread! I bought TRX takeoffs and am waiting to install.
For anyone wondering, the OEM Rebel stud length (with brake rotor still on) is exactly 40mm. Additionally, the stud "pocket" on the back of the TRX wheels measured in at just over 11mm.
I measured because i wanted to run the smallest spacer possible, I've ordered a 1.25 inch spacer (31.75mm) which should leave me with about 2-3mm of stud pocket clearance.
If anyone is interested i can take pictures of everything when i do the install.
Thanks