Pass the plate.

The steel plate that is!

I simply traced the old bottom plate, drilled out the holes, cut off some bits and offered it up to verify it would fit:

The stock bottom plate on the IRS was toast being cracked at two corners, bent all over the place and generally in a very sad condition. It had also been welded at some stage and I was shocked how flimsy it actually was when I started dressing it back into shape:

So a trip to the local metal yard had me return with some 4mm plate and I set to it with the trusty 100mm angle grinder. Do not under estimate what a 100mm grinder can do, especially if you have a lot of spare cutoff wheels on hand! Yes a plasma cutter etc is best, but for a one off, it worked just fine.
 I've also added a bracket on the front of the plate for a torque/reaction link that will run to the floor of the car and a rear bracket for jacking the car up. As the plate is 4mm, I can't forsee any issues jacking under the IRS. The torque link is so I don't end up with a repeat of pretzel IRS cage in the future.
 The bracket that will hold the front of the torque link to the body will also double as an intermediate exhaust hanger to hake the weight of the rear mufflers. Jaguar felt it necessary to add an exhaust bracket in this location on later cars and Aston Martin also thought it necessary, so I'll put one there. It will also allow me to tie the two exhaust intermediate pipes together at that spot, making everything a bit more rigid.

The old plate and the new:

The rear suspension cradle is finally in place and I have the radius arms etc all hooked up:

One rear hub has been assembled and measured for the correct shim, the other, I'm waiting on a second hand outer hub to arrive as the old one had seen the bearing race spin on it and make the bearing surface undersize. Someone has previously attempted to restore the hub to the correct size by whacking it with various punches, chisels etc, but it was still too far undersize.
I've hooked up the rear brake hydraulic line and handbrake cable as well:

  Wiring has also been run through the side footwell for the GM ECU. There is only single skin in this area, it is protected from the elements and there is enough room on the inside for the ECU and any extra wiring hook ups needed. Of course, once it is all installed, the harness will be taped and protected with conduit, but final routing hasn't been done in the engine bay as yet and I may need to snake a couple of extra wires through the firewall:

 Some cool parts have also arrived recently, but no photos of them at the moment. I have a brand new shifter cable, speedo cable and found a good used 90 degree speedo drive for the gearbox.
Also have a fair chunk of the exhaust system here ready to modify and fit. I'm going with NOS parts up to the rear mufflers, then have a pair of nice stainless hotdogs I picked up cheap.
 As you may know, rear mufflers always rust out first due to them running the coldest and collecting the most condensation on shorter trips.
 But all that cool, fiddly stuff will have to wait until next update when I get some photos and do some more work!