Transmission cross member frame

[Challenger6pak]

Before I spent a few hours jacking up cars to figure this out, I thought I might just ask.   I am working on a 73 Challenger.  I am wondering about the unibody frame that holds the torsion bars and transmission.  Is a 1970 the same as a 1973.  I know there are two different bolt in mount frames.  Can the 73 unibody frame be drilled to accept the 70 mount?  Are the frames the same between the two years with the only difference being the transmission bolt in mount?  With the floors out of the car, I can change the inner frame piece that the bolts go through, if he wants to stay original.  If the 70 frame is the same shape, I am going to help a guy save a 73 Challenger with a rusted frame.  Thanks,
Tod

[Challenger6pak]

I did not mean to stump everyone.  Has anyone had to redrill the bolt in transmission fram to fit the unibody transmission frame.  If so, once redrilled, did everything fit correctly?  If it did the curve of the unibody crossmember would be the same between the two years. 

[Bullitt-]

The reproduction piece from AMD shows as fitting all years
http://www.autometaldirect.com/ListItems/SubCategory/Floor/Torsion%20Bar%20Crossmember.aspx

[Challenger6pak]

Thanks for the link.  Below the one for 70-74 they show another one for 71-72.  Is this because of different bolt holes or a different shape.  I am guessing bolt holes.  If I can't find someone who has done the job, I'll have to get both cars up and compare.  I don't have a lift here or this would be easy. 

[74BlueFish]

I just cut my cross member out.  Inside the cross member are bushings that prevent the member from being crushed.  If the holes don't line up and you drilled and hit the bushing, that would be bad.  Trying to drill thru 2 inches thick of bushing. 

Dan

[Chryco Psycho]

 

You would need to open up the frame & install a sleeve for the bolt to go through & prevent crushing the frame .
 I have no clue how AMD is making 1 part for all years unless it has 6 or 8 holes through it

[Challenger6pak]

This I understand.  I mentioned in my first post that I would change over the inner piece that has both sleeves attached to it, as long as the member is the same.  I am guessing the inner piece with the sleeves does not come with the AMD piece.  You use the one that is in your old part and drill the crossmember to match.  It seems like the part is the same for all years, as far as shape goes. I guess I'll have to crawl under both cars an measure to be 100% sure. 
Thanks.