[lolife99]

ce134blu,... Welcome to the board with your 1st post!
Look at the link that n2trux posted.
It's not necessary to swap the crossmember itself.
I would get your '79 crossmember.
Strip it down and inspect all the parts.
Rebuild the a-arms.
Clean and paint.
Then when you have time to park your truck,... pull all the original a-arms and spindles off and replace with your freshly reconditioned parts.

Also swap the steering linkage and the P/S box from the '79.