As RSANDY said.(Kind words)I used the 3m bag sealer then painted it with HAMMERTITE HAMMERED GREY.The closest to mercury grey.

Bag sealer = £110
Hammerite = £15.
Poly bushes = £210
Powder coated suspension = £250
All new bolts,nuts and washers = £45

It,s not cheap doing an underbody resto,but do it right and it will last a good 10 years.
Well worth it for the way it looks and peace of mind.
No more crossing your fingers come m.o.t time.