Too many days on the same topic.

But then what can you expect when you can only get into the shop part of one day per week.

Here is the offending cross member. It is held to the frame rails with these three rivets on the top of the c-channel and two more below, on each side.

On the donor frame, where I removed the replacement member, I used the cutting torch and blew the heads off. I did not want to put that much heat to my keeper frame so I took a few more minutes and ground the heads away.
You'd think that once the head was gone a few taps with the punch would pop them out. Wrong! These babies are tight. Both ends of my drift now look like mushrooms.
The member is out. Ready for the new(er) one.
Here are the two cross-members side by side. The taller one (lower) will accomodate the much larger (taller) diesel fuel tank.
This side-by-side shows the difference in depth of the two frames. On the left is the crew member out of the 7" frame. Both the top and botom fit inside the c-channel. On the right, is the '92 cummins member with the 6" frame. It mounts under the top and under the bottom of the c-channel, but the hump in the lower support makes it overall the same size at the other (lucky).

Here it is pined in place. The top holes all line-up perfectly. The bottoms will meed some massaging.

The holes were just shy of 7/16. I drilled them out to 7/16 and mounted the top with tranny crossmember bolts from the donor truck. These were also 7/16 bolts.

Here you can see what I have to deal with with the lower mounting.

The gap it exactly one inch.

So, some one inch spacers were in order. I used 1" heavy-walled square tubing.

Four spacers, cut and drilled.

All bolted in.

I used grade-8 bolts (overkill) and these locking nuts. Now I get to take it all back out for painting.