I'm planning on making my T56 swap cross-member, any suggestions on what type of steel to go with(diameter, wall thicknesses ect.) Thanks- Eric

Anyone?

I'm not exactly familiar with a manual swap, and from the wording you used it seems like your looking at round tubing?

I would suggest using 3/16" for all of the flat mounting parts (where it mounts to the subframe, where the tranny mount goes, etc), and for the tubing portion you might want to look at something like 1 1/2" or 1 5/8" with .120 wall thickness. It might be cheaper to buy ERW (it has a seam) tubing instead of DOM (no seam). Just so you know, the last time I bought tubing it was cheaper to get 1 3/4" than 1 5/8", so thats what I bought. As for the type of steel, regular hot rolled steel should be fine for this application.

BTW, what rod/wire are you using to weld? ER70S-6 is a good, all around filler rod/wire for steel that could have mill scale, rust, or oil contamination. It's typically what I use because it can be used with less than perfect base metals.

as far as square or round, it doesn't really matter, I said diameter and wall thickness, when I should have just said size. whatever would provide the most clearance would be best, because I would prefer to run a dual exhaust, so I need all the room I can get!

1-1/2" or bigger would be huge under there! I would probably go with 2 tubes going across about 7/8" dia and about 1-1/2 - 2" center to center spacing. Then, weld a flat piece between them with a hole for your tranny mount. attach them the a 3/16" or 1/4" thick plate for the mounts to the frame. However, if you want clearance for exhaust, a straight shot across under the tranny wouldn't be ideal, for me anyway. What we did on my car for exhaust clearnce was... took the stock cross member, split a piece of pipe, welded it on top of the cross member, then cut the stock steel from between the pipe. Now, the exhaust pipe sits nicely tucked up in there.

^^ that is a good idea. I got the spohn cross member, and I don't remember what the overall height of it is so I was just trying to guess off the top of my head. Good luck with the build!