since iv owned my car theirs been different bolt sizes for transmission cross member it hasn't bothered me much with the stock member, but now that i have my UMI peace that uses all 6 bolt holes its a different story. on my frame rail 3) of the bolts are bigger then original, 1) of the bolts is so over sized that you can basically start threading it into the cross member by it self. the other 2) are stock and are rusted so much i would be afraid to tap them. i know a few other people that have either ran into smiler problems or that had broken the head off a bolt etc. Iv have even heard of people welding the cross member to the frame this is obviously something i don't want to do! i have few ideas as to how to go about fixing this so all 6 bolt holes are the same i want to try to keep it simple. i thought about putting in high grade studs relative to the same size as stock then welding them to the frame rails where the original bolt holes would be, then using lock washers and nuts to hold ever thing in place. i thought about drilling out all the original holes and welding nuts behind the frame rails making accessing holes by whole saw through the floor boards to weld If anyone else has some ideas or input let me know. . .

Your best bet would be to gain access into the frame area from the top (through the floor) by cutting an accessway in the sheet metal. Then you can make up a plate that is the same width as the inside of the framerail. Make the locations needed for the crossmember bolts and do one of two things. You can use a piece of thick steel for the plate (3/8"-1/2" for example) and sinply drill and tap the holes in the plate, or you can weld nuts onto a thinner piece of plate. Personally I'd use the thick plate and just tap it. Then you can tack the plate into the framerail and close the hole from the top side and weld it back closed. I've used repairs like this with subframe mounts in early Novas and Camaros with good results.

hmmmm. what do you think of the stud idea? i wanna keep it simple and i think that would work too

right?

The problem I see with the studs is that they will lose their heat treatment and therefor strength when you weld them. You will also have no wiggle room as the studs will be permenantly in place, unless you make the holes in the crossmember oversize.

i think studs would be easy to do. i think im going to go that route.

How about trying to put in a threaded plug, weld it in-place then drill and tap to the size? Anyone have any other ideas im still thinking about just dropping in some bolts from the top and tacking them in place...

Yeah I am at the same quarrel. I put in a torque arm relocation crossmember and it has 3 holes for bolts on each side. Well I used the factory bolt holes. I am thining of just putting a bolt in from the top on the front one. Weld it into place and use the very front as a stud. Thier is something about it. I would feel better with another bolt in it. Being I am going to pull my transmission out here in the next couple of weeks to install a newer torque converter I will fix this at the same time.

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maybe re-tap and try thread adapters and some way of holding them in place?

Went ahead and drilled out pilot holes from the bottom using a 3/16th 12" drill bit i cut down to 8" and then used a 32mm hole saw from the top, i ordered some M10 x 1.5 10.9 grade nuts and bolts all see whats going to work best welding in the nuts or the bolts.