I'm sure there is a post in the archives about this... There is a special custom HP bracket on the left. It is a heavy piece of steel - and it MUST be, due to the weight and movement (swing out) of the unit. I'm used to finding ways for one person to do a two man job when mounting things in racks, but just don't do it with the 7970 - you will get hurt. I had to get someone to help mainly because it's not just sliding in on some kind of rails. You have to literally hold the unit in place in mid air in the rack while getting to bolts and holes to align that you can't even get to from your side of the swingout. ISTR it's around 150# or so. Even with two people, there was a lot of huffing and straining - and that is with the special bracket that is designed to sort of hold it in place (it doesn't really) while you bolt it in.
I've probably had around ten 7970's go through my shop, and only one of them ever came with that bracket. It is almost always lost. So... I had a friend of mine that owns a machine shop fabricate a new mounting bracket for the 7970. I think I had him make around 8 or so, and I sent them off to other collectors for the cost of having them made or shipping or smth. These brackets are 100% identical to the originals and made from steel that is at least as strong as the original, probably more. I think I may have an extra one of those brackets that was made, will check. J