Jeff,
This is my 73 crossmember, is this what you are asking about. As for the 700R4, on yours you will need to drill the holes.
__________________
Chris Lucas
1973 Chevy C-10
1978 GMC Jimmy (2WD) - SOLD
1987 R10 twin turbo LS
1991 R3500 SRW CrewCab
1985 K5 diesel swapped project
1989 K5 2WD conversion w/ Vette susp Project
Captkaos Customs
73-87chevytrucks.com