I've seen pictures where guys have cut out the crossmember arch that goes over and across the tranny,
then they tied the two cut "ends" together with a reinforced straight piece, under the tranny.

Does anyone make a bolt-on piece that does this ? I'm talking B and E body. A-body I don't know.

You would need to do this if your putting in a physically bigger tranny and need to cut out the tranny tunnel.

Understand the forces induced here if OEM TB's are still in play, plus the weight the trans mount carries.
If it is a converted coil IFS, the forces are much reduced on this crossmember.
Crash worthiness is another discussion, a cage with a dash bar kinda also needs a lower member to keep the cage in place in that area.

Yeah I did that about 30 years ago on my Coronet when I switched over to a Doug Nash 5 speed. It has worked okay over the years. I have a picture of the crossmember that I built back then. I've replaced it with a better design but I don't think I have a picture of the new design.

I cut the floor brace out as needed and on the passenger side splice in a 180°bend of 1-5/8 or 1-3/4 tubing to the oem bracing. On the driver side you can land the tubing perpendicular to the boxed section of the brace. I holesaw through the bottom for weld access.

Thanks guys, I could probably practice my butchering techniques,
but I could have sworn I saw somebody that made one.
Can't remember what I put in the search engine.

I would think that someone could map out the floor contour.
Then fab tooling (maybe using CAD or whatever) to make a shallower but thicker replacement piece.
Or maybe make a 1/4" plate, formed to match the floor contour, for welding in.
There would seem to be a market for such a thing.

BigDad made a really nice crossmember for his silver 64 Plymouth with pics posted many years ago.

Gus

US Car Tool sells a variety of Mopar transmembers for different swaps and such.
https://store.uscartool.com/

Thanks Andy, I guess those will all work with the OE top connector hoop cut out.
Possibly I'm trying to remember something that I never actually saw.

If I used one of those crossmembers, I would increase the size of the bolts holding it in.
The forces from the T-bars cannot be allowed to flex the floor area.

Here's an option for a 66-70 B-body. It looks beefy enough to withstand the forces of the torsion bar suspension.

Hope this helps.

https://www.holley.com/products/engine_swap_parts/mounts_and_crossmembers/crossmembers/parts/BHS539

That Holley design looks a lot like what I was thinking, but it seems to capture the trans crossmember.
Not the end of the world, though, I suppose.
But I'd prefer a welded upper arch; maybe a short sleeve at each side for the T-bar member.

That Holley thing looks interesting.

1/2" steel strap?

I used a 1/4" steel plate about 4 inches wide and just over 2 feet long welded through the floor pan to the top on the remaining cross member. I had to heat the steel band red hot to bend it and spent time getting it to match the original floor's contour.

I also welded most of the original torsion cross member solidly to the floor pan when I installed the full US Cartool Chassis Stiffening kit. I cut the actual tunnel portion of the cross member down flush, but left the factory flanges and boxed the bottom of the trimmed crossover back in with like-sized steel. I did this fab work with the torsion bars out.

In my case, this was done to fit an overdrive automatic. I may soon be doing further modification, as I'm putting in an even larger automatic to accommodate a more powerful engine.

These are the only pictures that I currently have of the lower modified crossover. I was able to retain the factory cross member bolt locations.