I am just about done my zf5 swap. It has been that bad of a swap. But I am having an issue with trying to get the crossmember to line. I know the transmission is longer. I know some forums say they 1moved the cross up an inche. My question is did they also move the gussets up too. Mine bolts are seized in there. Just any tips of thought would be greatly appreciated.



Have a wonderful day 😁

 

The zf takes special gussets that have more offset to them. So the upper holes of the gussets line up with the original holes, the lower holes of the gussets line up with the new location of the lower crossmember.

I had a donor truck that I took the zf out of, so I could compare and get what I needed. I had a little bit later truck that originally had the zf as a option, so those frames already had the lower holes drilled to move the lower crossmember back.

I was looking at it, and thought if I didn't have the correct gussets for my swap, what I would do is use the original gussets, move them back to the new location, and the see where one of the original holes on the upper part of the frame lines up. I would think at least one original frame hole would be in the area of the gussets, I would mark the gussets, take them out and drill the new hole in the gusset. Then re-install them with one bolt in the upper part of the frame. The upper part of the frame looks very difficult to drill a new hole, I would think one bolt would be enough to hold it. Some people leave the gussets out, I do not think that is a good idea.

 

If that's the crossmember for the ZF5, that must be for a later truck as well.

The one I used from the '89 donor truck looks entirely different, and wraps around the outside of the frame. Now that I think about it, it could actually be a 4WD specific crossmember since I swapped in a transfercase as well.

Most of the holes were there on my frame, but I did have to drill two on the driver's side of the frame; interestingly, the holes for the passenger side were already there.

 

Mine was a 1989 model, and the donor was a 1989. It mounted on the inside of the frame like the picture above, but I have seen the type you are talking about that mount to the outside of the frame.

My 1989 originally had a c6 and was 4x4. When I was swapping and comparing, I found the lower crossmember that went from frame rail to frame rail was the same piece for the zf and the c6. In this application only the upper gussets were different.

 

I modified my gussets with a short extension. This way I was able to move the mounting point rearward and leave the existing bolts in place in the upper frame rail. If I recall correctly, I even with the correct M5OD crossmember, I still had to relocate the crossmember holes rearward 1 3/16". Below is a picture of one of my gussets showing the extension I made. It was just a piece of angle iron, so it was nice and strong. It worked great.