3/4 ton have same crossmember as 1/2 TON?

[wbr775]

so my neighbor will sell me a 3/4 ton 75 Chevy for $100. I have a 69 4 wheel drive 1/2 ton that i want to convert to 2 wheel drive. my question is can i use the crossmember and a-arms from the 2 wheel drive 3/4 ton truck and change out my crossmember in my 69 to make it 2 wheel drive? is the 3/4 ton crossmember different from a 1/2 crossmember? will it bolt right up? i know the hubs are diffrent since it is 8lug but i planned on using drop spindles so no problem there. any help would be greatly appreciated thanks Ian