New Member With Lots of Questions

[maverickmk]

Well, I am finally able to post here. Refer to the Welcome Area for specifics.
I have a 1969 GMC that I recently purchased and need some assistance with a few things.
First being the addition of disc brakes. From what I have been told a cross member from a next gen of Chevy/GMC's will bolt in with only enlarging a couple of holes. I got one from a 1984 and did a rough measurement of the bolts holes that are right above the upper control arm and it appears that the original holes are closer together than the assembly I have. Is this possible, or did I measure incorrectly? I did a rough measurement on the upper control arms as well, and the originals measure smaller than the one from the '84. What are my options? Any ideas or suggestions?
Here is a picture of what I picked up today.



If I can get the 5 lug disc brake setup figured out, I would like to get 5 lugs in the rear as well. I found a site that sells axles that are supposed to fit. Here is the link: https://www.speedwaymotors.com/1965-...MaAqtzEALw_wcB

Any idea if this will work? It has a 12 bolt, but I haven't looked at the casting numbers yet to verify what exactly I have.

I have more questions, but will wait until I get into the brake situation right now.
Here is a picture of my truck.