Sorry to hear about that. Everyones Nightmare.
Are you aware of what a big job this is. Actually I`ll rephrase that. Do you have the ability to have the car off the ground with a pit under it, or is this being done "on the driveway"?
Do you have a complete toolkit (proper) to do this.
The reason I ask is that I have just replaced the Rear Axle Carrier and both trailing arms, shocks etc on a 535i, and it is not a fun job IMO.
You`ll really need two of you to get the damn diff out and back in, and I recommend the Bentley 5 Series manual for all the torque settings an pics to put it back together again. There are quite a few bolts and bits, as the entire braking system has to come off, so stating the obvious, label the bolts and put in little plastic bags.
This followig may be considered a "thinks aloud".
My 535i was considered a writeoff because to have a BMW dealer do the job was £3500 inc parts.
I did it (am doing it) after buying the complete rear of another 535i for £210 delivered.
I would not throw the car away.
Now your M5 needs more than this. If by "complete rear suspension", you mean trailing arms, brake system, hoses n pipes, driveshafts etc, plus the whole lot again, isn`t it cheaper to sell it and start again. Plus you have the aggro of the self levelling system I avoided.
Surely the insurers have paid the value of the car, and you and I know that there are several bits on a M5 which are highly in demand.
When I bought my 1990 M5 3.6 in July, I was vying with scrap dealers
to buy it. The car was worth its value £5000-6000 in parts according to them.
Would it not be worth using the insurance money you have recieved, then selling the perfectly good and desirable M5 engine, and the gearbox (like gold dust, them).
Add in complete leather interior and you still have the Windows, windscreen, electric motors, ECU, Exhaust, OBC and wiring loom.
I know you then have the aggravation of tracking down another M5, but this may be the way to go.
PS. If you don`t want to do this, and it would break my heart to do it myself if I was in this position, then I got my bits from going to www.autotrader.co.uk
and clicking on the salvage section.
This allows you to email "400" scrap dealers up and down the country with one e-mail. You then await them to all call you. It works.
If you are friendly with your local BMW dealer, then it may be worth looking up on the BMW computer some part numbers.
Things like the tie rods, steering linkages, axle carrier and quite probably trailing arms are the same as the 535i that was taken to Motorsport GMBH to become your M5.
The brakes are not obviously, but a scrap dealer generally cuts brake hoses and abs sensor cables when they take trailing arms off. The hoses etc will have to be rebought from BMW Dealer.
Is your suspension missing or bent/broken?
If its bent, then at leat the brake hoses, bowden cables etc will be intact. If its missing, then this is going to be a long haul.
If there is anything I can check with you at my local dealer then mail me, otherwise, having just replaced the axle carrier on my 535i (M5 is based on it as you know), then if there is any advice you need on taking it to bits, then mail me.
I cannot help on the self-levelling system, as even the bentley manual does and overview of it, but says take to main dealer as they have the tools.
PPS. If you need trailing arms, get them WITH the wheel bearings. My dealer wants an outrageous £80 to fit, plus the wheel bearing (!) and thats if I take the trialing arm off the car to them
Its special tools to seat them properly, but I bet 95% of the time is taking the arm off the car, and thats already done.