Transmission crossmember bolt sizes?

I'm finally back working on my butchered '67 Barracuda. Originally a slant-6/904 car, a previous owner put a 360 and A833 trans in, but never finished the job (it's also got a GM 8.2 rearend, Dog knows why). The crossmember the PO put in is some kind of welded up hack job, and I was unable to get the shift linkages to work with it. According to Dan Brewer, I have the correct shifter and linkages for this A833. I have a crossmember from a '71 Dart's 904, and everything lines up, except the 1/2" bolts (non-original, looks like grade 2 Home Depot stuff) which worked with the hacked up crossmember don't go through one side of the factory crossmember. It looks like the bolts should be a very specific length where the body of the bolt goes through the frame, but the threads are smaller diameter where they come through the other side of the factory crossmember. I could drill it out of course, but I'd rather not.

TL;DR version -- Are crossmember bolts "special"?