I hate to have to disagree but I can't see any way that ST165 crossmembers will help if your doing a 3sgte swap into a ST162. The ST165 front to rear crossmember is angled more to the drivers side at the rear in order to make room for the drive shaft that goes from the tranny to the rear diff so the rear of a ST165 crossmember won't even bolt up to the frame of a ST162. So at best you would need to use the original ST162 front to rear crossmember and you could swap the ST165 side to side cross member in and its 6 side bolts will work but the center bolt that attaches the side to side cross member to the front to rear crossmember will not work now so I don't see any advantage in useing either of the ST165 crossmembers in a ST162. I think the front to rear crossmember with the motor mounts still attached is the ST165 one The only way I could see these being needed is if you wanted to turn a ST162 into an All Trac but we've been over that topic a few hundred times and why it's not feasible.
Be very carefull, Dave is right and the two aren't compatible. Look at the engine cover mounts as well, you can't fit 162 covers on a 165 without re-drilling holes etc. Also the ST162 86-87 and 88-89 crossmembers are different as well and you can't swap them as the chassis bolt holes are different, the rubbers are different too Here I cleaned up an 87 to fit on TEMS (88), the bolts on the 87 are wider (right) and the mounts are way different too