C20 Control arm differences

[rpmerf]

Can I bolt 73-87 C20 upper and lower control arms to my 1970 C20 cradle without drilling? If so, will the geometry be the same? Can I still use my 1970 springs?

Background:
I have a 1970 C20. I bought a 1983 C20 to sacrifice for my disc brake swap. The 83 comes with a new in box set of upper control arms with shafts and ball joints installed. I'm wondering if I can get a set of lowers and use them for the swap. I'd rather not swap the cradle. If swapping control arms doesn't work, I plan to install the 73-87 ball joints in my 1970 control arms.

[chevy_mike]

Yes, you can swap the arms to your 70 but you also need to swap all of the steering to the later model one or you might have to use adapters for connecting the inner and outer tie rods. Not 100% sure if this is the can on C20's but I know it is on C10's. If the C20's are like the C10's, you can actually put the later model ball joints into the original arms, if they are in good shape. Then use the later spindles/steering.

[AZ 67 C10]

What's the difference in ball joints for the later models? Bigger?

[chevy_mike]

Originally Posted by AZ 67 C10

What's the difference in ball joints for the later models? Bigger?

I am not sure about the C20 stuff, as I am not as familiar but I know the C10 stuff, yes the ball joints were bigger.

[LoX_69]

From what I vaguely remember the +73 ball joints are have a larger diameter shank. On my 69 C20 I used the original control arms and replaced the ball joints in order to use the +73 spindle/Disc brake assy I got from a donor truck.

[rpmerf]

Thank you. I will try bolting in the new arms when I do the swap.

[chevy_mike]

Yeah, I should have been clearer, the shank is bigger, I think the actual ball joint part to fit the a-arm hole is the same.

[Bentbolt]

I tried to put 73-87 arms on my 65 and the center to center of the hole in my crossmember are different then the Ubolts I got.