Hi folks there seems to be a lot of knowledge out there on this conversion but it's hard to find solid info on it. I thought I'd kick things off with my T5 - Clevo conversion.   Starting out with a C5TA (1965 Truck) factory cast bell to suit a wide-pattern toploader:     Left side with T5 box:     Right side:     Holes marked & pilot drilled:     So as you can see the top two holes are too close to the old ones and are definite weak spots, compounded by the fact that they also don't have bosses cast for them. They'd be lucky to have 1/4" of meat to thread into. From the good advice from folks on here, I'll try and silver solder them in a makeshift furnace and solder some studs in as well. I've drilled and tapped M12x1.75 threads for them. This is a mock-up using some M12 set screws wound in from the inside:     Next step is to find some studs that are the right length and solder them in as well as plug the top two factory holes with cut-off 7/16 bolts and solder them in too.