PCIE 2 and PCIE 3 spec and connector solutions for these specs from FCI

PCIE2
http://portal.fciconnect.com/Comergent//fci/documentation/mezzostak_7mm_pcie.pdf
http://portal.fciconnect.com/Comergent//fci/documentation/mezzostak_4mm_pcie.pdf

PCIE3
http://portal.fciconnect.com/Comergent//fci/documentation/bergstak_12mm_vs_pcie.pdf