<p style=”text-align: right;”>I have seen a few Exsis with bad underside corrosion, the chassis design has a few rust traps also I think the grp body and lack of rust on the bodywork gives owners a false sense of security. But your post the rust seems quite advanced, if you patch up a couple of holes, rust will probably appear somewhere else. Find a specialist rustproofing independent, there is a very good one one Johnstone in Scotland maybe a bit far but it’s worth travelling for a recommended outfit. Get the underside stripped up of paint and old underseal, all rust cut back to the metal and welded, then properly painted and rustproofed. The exsis although old is not like a car it is far more valuable so work like this while being uneconimical on a similar age car, is worth it for an exsis, have the work documented and photograph, in case you wish to sell.</p>