Putting a 2004 chevy seat in my 71

[KAILUAZ]

Not sure if these are the same seats. They were out of a 2001 1-ton.
I was able to sit the seats on the floor and they lined right up. In fact one of the bolt holes lined up with the stock location. I just drilled out the treads of the original mount.
I left the center seat out as I'm going to do a center counsel later.
I used angle iron and grad 8 bolts. I did have to use bolts with allen heads because there was no way to fit a wrench in the seat rails to tighten them.
No need for power for the seat belts to work, they use enertia.
Hope this helps;