For those who don't know, I have 62' 80 with SBC 350, Dana 44s Front & Rear (Detroit & Spool, 4.88s, & discs all around), going to a SM465 & Dana 18.

I got the new Tranny in this week, & I have old crossmember that was fabbed up years ago.
The good news is it looks like it's a perfect fit.
I just removed the old Parking Brake lever, & just have to Mount it (the crossmember) about three inches further to the rear.

I was originally planning on just drilling new holes, & puting some 1/4" plate (about 4-6" long) on the outside of the frame rail to re-inforce it.

With all the flex I'll be gettin while wheelin', is this a good idea?

Or should I cut a larger hole & run tube/pipe through to absorb (sp?) the pressure of the bolt onto the frame rail?

Here's the crossmember with the old tranny...
http://pics.montypics.com/mochamike/2003-03-07/tranny_crossmember_2.jpghttp://pics.montypics.com/mochamike/2003-03-07/tranny_crossmember_1.jpg
Here is the new Tranny & TC mounted:
http://pics.montypics.com/mochamike/2003-03-04/tranny_mounted_top.jpg http://pics.montypics.com/mochamike/2003-03-04/tranny_mounted_bottom.jpg

I would definately sleeve the holes with the tube/pipe.

I agree with Ben. What size bolts are they? 1/2" shc 40 pipe works well with 5/8" bolts. Just run a 5/8" bit through it to clean it up a bit. I would weld the pipe to the frame also.:)